Identification, Nomenclature, Genome Sizes, and Ploidy Levels of Liriope and Ophiopogon Taxa

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  • 1 Mountain Crop Improvement Laboratory, Department of Horticultural Science, Mountain Horticultural Crops Research and Extension Center, North Carolina State University, 455 Research Drive, Mills River, NC 28759-3423
  • 2 Department of Horticultural Science, North Carolina State University Herbarium, Department of Plant Biology, North Carolina State University, Raleigh, NC 27518
  • 3 Plant Delights Nursery, 9241 Sauls Road, Raleigh, NC 27603

Liriope Lour. and Ophiopogon Ker Gawl., collectively known as liriopogons, represent important evergreen groundcovers grown throughout the world for their ornamental features and medicinal qualities. As a result of the diversity of desirable traits and evidence of wide hybridization, there is considerable potential for breeding and improvement of liriopogons. However, confusion over taxonomy and proper identification and lack of information on ploidy levels and cytogenetics of individual clones and cultivars have constrained breeding efforts. Objectives of this study were to validate the identification and nomenclature and determine genome sizes and ploidy levels for an extensive reference collection of species and cultivars of liriopogons. Identification was accomplished using existing keys, nomenclature was corrected, and numerous accessions were reassigned based on morphology. Genome sizes were determined by flow cytometry. Ploidy levels for each species were confirmed by traditional cytology. Results confirmed a basic chromosome number of x = 18 for liriopogons with aneuploidy, polyploidy, and cytochimeras found in some cases. The Liriope examined included diploids (L. graminifolia, L. longipedicellata, L. minor, and some of the L. platyphylla), tetraploids (L. muscari and the remaining L. platyphylla), and hexaploids (L. exiliflora and L. spicata). The Ophiopogon studied included diploids (O. intermedius, O. jaburan, O. planiscapus, and O. umbraticola) and a tetraploid/hypotetraploid species (O. japonicus). Monoploid (1Cx) genome sizes varied by genus and species with 1Cx values ranging from 4.27 pg in L. exiliflora to 8.15 pg in O. jaburan. These results clarify nomenclature and taxonomy and provide specific information on genome sizes and ploidy levels of cultivated liriopogons. This information and associated reference collection will aid future taxonomic revisions and enhance efforts to develop new cultivars of liriopogons.

Abstract

Liriope Lour. and Ophiopogon Ker Gawl., collectively known as liriopogons, represent important evergreen groundcovers grown throughout the world for their ornamental features and medicinal qualities. As a result of the diversity of desirable traits and evidence of wide hybridization, there is considerable potential for breeding and improvement of liriopogons. However, confusion over taxonomy and proper identification and lack of information on ploidy levels and cytogenetics of individual clones and cultivars have constrained breeding efforts. Objectives of this study were to validate the identification and nomenclature and determine genome sizes and ploidy levels for an extensive reference collection of species and cultivars of liriopogons. Identification was accomplished using existing keys, nomenclature was corrected, and numerous accessions were reassigned based on morphology. Genome sizes were determined by flow cytometry. Ploidy levels for each species were confirmed by traditional cytology. Results confirmed a basic chromosome number of x = 18 for liriopogons with aneuploidy, polyploidy, and cytochimeras found in some cases. The Liriope examined included diploids (L. graminifolia, L. longipedicellata, L. minor, and some of the L. platyphylla), tetraploids (L. muscari and the remaining L. platyphylla), and hexaploids (L. exiliflora and L. spicata). The Ophiopogon studied included diploids (O. intermedius, O. jaburan, O. planiscapus, and O. umbraticola) and a tetraploid/hypotetraploid species (O. japonicus). Monoploid (1Cx) genome sizes varied by genus and species with 1Cx values ranging from 4.27 pg in L. exiliflora to 8.15 pg in O. jaburan. These results clarify nomenclature and taxonomy and provide specific information on genome sizes and ploidy levels of cultivated liriopogons. This information and associated reference collection will aid future taxonomic revisions and enhance efforts to develop new cultivars of liriopogons.

Liriopogons (most recently Ruscaceae s.l. Hutch, formerly assigned to Convallariaceae Horan., Asparagaceae Juss., Haemodoraceae Arnot, Ophiopogonaceae Kunth, and Liliaceae Juss.) (Kim et al., 2010) comprise a class of valuable evergreen groundcovers (Skinner, 1971). Liriopogons are native to China, India, Japan, Korea, the Philippines, and Vietnam with Liriope consisting of approximately eight species (Chen and Tamura, 2000a) and Ophiopogon consisting of ≈65 species (Chen and Tamura, 2000b). Popularity of liriopogons is attributable, in part, to their adaptability (Li et al., 2011) and versatility in the landscape, easily filling the roles of groundcovers, foundation plants, edging and massing plants, and understory plants (Fantz, 1993).

The complex taxonomy of liriopogons has been developing since the initial designation of Convallaria japonica by Thunberg (1780). The following centuries resulted in many genera designations (Anemarrhena Bunge, Chloopsis Blume, Convallaria L., Flueggea Rich., Liriope, Mondo Adans., Ophiopogon, Polygonastrum Moench, and Slateria Desv.) and common names (aztec grass, bordergrass, lilyturf, liriope, mondo grass, monkeygrass, and snakesbeard) (Fantz, 1993; Nesom, 2010). Nevertheless, liriopogons’ attractiveness, resistance to pests and diseases, hardiness, and utility in the landscape have made them important nursery crops. Wholesale values of liriopogons in North Carolina are estimated to be over $41 million for 2009 (Trueblood, 2009).

Much confusion surrounding liriopogons lies in morphological similarities between the two genera. Both Liriope and Ophiopogon are acaulescent, evergreen herbs that set summer/fall racemes of small pink to purple or white flowers. Floral whorls are found in multiples of three (dichasia to compound dichasia to small cymes) (Fantz, 2008a). The perianth has six indistinguishable sepals and petals and six stamens. Fruits of liriopogons are blue/black and berry-like or a three-celled capsule (Fantz, 2008a).

Anatomical studies by Cutler (1992) and Rudall (2000), as well as a molecular marker investigation by Mcharo et al. (2003), concluded that similarities between Liriope and Ophiopogon were too great to warrant separation into two genera. However, morphological studies by Bailey (1929), Conran and Tamura (1998), Hume (1961), and Skinner (1971), molecular phylogenetic studies by Kim et al. (2010), and a molecular marker study by Li et al. (2011) provided evidence supporting separation of Liriope and Ophiopogon.

A recent overview of Liriope and Ophiopogon cultivated in the United States by Nesom (2010) found floral characteristics the best method of distinguishing between Liriope and Ophiopogon, supporting Fantz (2008a). Flowers belonging to Liriope are erect with corollas cupulate to rotate and free anthers with apical poricidal openings and long filaments. In contrast, flowers of Ophiopogon are nodding with corollas campanulate and connate anthers in a column, which narrow apically, dehisce longitudinally, and have subsessile filaments (Fantz, 2008a; Nesom, 2010).

In addition to the historically complex taxonomy of liriopogons, nursery practices including sexual propagation of cultivars, plant substitution, mislabeling of cultivars, and seedling invasion of stock plants have resulted in cultivar degradation within the nursery industry (Fantz, 1994). Fantz (1994) investigated 22 named species and 88 labeled cultivars of Liriope and Ophiopogon collected from nurseries and found 17% of germplasm misidentified to genus and 36% misidentified to species.

A variety of ornamental features such as flower color, inflorescence height, inflorescence branching and fasciation, fruit color, foliar variegation, and medicinal qualities such as steroidal glycosides in tubers (Cheng, et al., 2006; Wang et al., 2012; Yu et al., 1996) indicate a high potential for breeding and improvement of liriopogons. A recent study by Zhou et al. (2009) also demonstrated that hybridization between tetraploid L. spicata and diploid Ophiopogon may be occurring naturally in the wild, suggesting new possibilities for breeding between genera in liriopogons. However, breeding systems and cytogenetics of liriopogons are complex. Previous karyological studies have demonstrated the basic chromosome number for liriopogons to be x = 18 (rarely x = 17) with high levels of polyploidy in many species (Table 1). Also, Fukai et al. (2008) investigated ploidy level and relative genome size through flow cytometry of six species (plus cultivars) of liriopogons (Table 1). Oinuma (1946) reported polyploid forms of liriopogons exhibited increased vigor and grew over a wider geographic distribution than diploid forms. In addition to various ploidy levels, many studies have reported liriopogons to be uniquely tolerant of high amounts of aneuploidy (abnormal number of chromosomes) and cytochimerism (different chromosome numbers among cells in the same plant) (Table 1). Therefore, evaluating the cytogenetics of individual clones and cultivars is critical to developing a breeding strategy for liriopogons.

Table 1.

Previous cytological and cytometric analyses of liriopogons.

Table 1.

As a result of the wide range of ornamental traits found in liriopogons and evidence of interspecific and intergeneric hybridization, there is considerable potential for breeding and improvement of liriopogons. However, these efforts are constrained by confusion over proper taxonomy, lack of information on ploidy levels, and lack of information on cytogenetics of individual clones and cultivars. Objectives of this study were to 1) validate the identification and nomenclature; and 2) determine genome sizes and ploidy levels for an extensive reference collection of liriopogons.

Materials and Methods

Plant material.

Accessions of diverse species and cultivars of liriopogons were collected from nurseries, arboreta, and various individuals (Table 2). Containerized and field specimens of liriopogons were examined in this study including L. exiliflora (L.H. Bailey) H. H. Hume, L. gigantea H. H. Hume, L. graminifolia (L.) Baker, L. longipedicellata F.T. Wang and T. Tang, L. minor (Maxim.) Makino, L. muscari (Decne.) L. H. Bailey, L. platyphylla F. T. Wang and T. Tang, L. spicata (Thunb.) Lour., O. intermedius D. Don, O. jaburan (Siebold) Lodd., O. japonicus (L. f.) Ker Gawl., and O. umbraticola Hance. Multiple herbarium vouchers were collected for nearly all taxa and identified based on previous descriptions and available keys for liriopogons (Broussard, 2007; Chen and Tamura, 2000a, 2000b; Cutler, 1992; Fantz, 2008a, 2008b, 2009; Hasegawa, 1968; Liu et al., 2007; Nesom, 2010; Tamura, 1990; Tanaka, 2000, 2001a, 2001b, 2001c; Zhang, 1998). The primary collection will be deposited at the North Carolina State University Herbarium, Department of Plant and Microbial Biology, Raleigh, and the Herbarium of the U.S. National Arboretum.

Table 2.

Genome sizes and estimated ploidy levels of cultivated Liriope and Ophiopogon.

Table 2.

Survey of genome sizes and ploidy levels.

Genome sizes and ploidy levels were determined by traditional cytology in combination with flow cytometry. To prepare samples for flow cytometry, leaf tips (≈1 cm2) from expanded leaves of each taxa were placed in petri dishes containing 500 μL of nuclei extraction buffer (CyStain ultraviolet Precise P Nuclei Extraction Buffer®; Partec, Münster, Germany) and chopped finely with a razor blade until completely incorporated into buffer. Resulting solutions were pipetted through CellTricsTM (Partec) disposable filters with a pore size of 50 μm. Then, 2 mL of a nucleotide staining buffer solution combined with 6 μL RNase A and 12 μL propidium iodide (CyStain PI absolute P; Partec) was added to the filtered solutions. Samples were refrigerated (4 °C) and incubated for over 30 min, and the resulting stained nuclei were analyzed with a flow cytometer (Partec PA II; Partec) with counts exceeding a minimum of 3000 cells per analysis.

Mean fluorescence for each sample was compared with an internal standard of known genome size (Pisum sativum L. ‘Ctirad’, 2C DNA = 8.76 pg), and holoploid, 2C genome size (i.e., DNA content of entire non-replicated chromosome compliment irrespective of ploidy) was calculated as 2C = DNA content of standard × (mean fluorescence of sample/mean fluorescence of standard). Monoploid genome sizes (1Cx = DNA content of the non-replicated base set of chromosomes, 1x) were calculated for each sample as (2C genome size/ploidy level). Monoploid genome sizes were subjected to analysis of variance by genus and species, and means were separated using Fisher’s least significant difference (Proc GLM; SAS Version 9.2; SAS Inst., Cary, NC).

Chromosome counts were performed on selected species of liriopogons to confirm ploidy levels and to allow for calibration of ploidy level with genome size. A root squash technique was used that allowed for direct counting of chromosomes. Actively growing root tips were collected and placed in freshly made vials of pre-fixative solution (2 mm 8-hydroxyquinoline + 70 mg·L−1 cyclohexamide) at room temperature (22 °C). After remaining in the dark for 3 h, all vials were moved into a dark refrigerator at ≈4 °C for 3 h, yielding a total pre-fixative treatment of 6 h. Root tips were then rinsed with distilled water and transferred to a freshly made fixative of 1:3 propionic acid to 95% ethanol and left at room temperature overnight. The following day, a 1:3 hydrolysis solution of 12 M HCl to 95% ethanol was made for the root squash procedure.

For each root squash, a fresh root was removed from the fixative and hydrolyzed for 12 to 20 s before being moved to a clean slide. The root tip was excised using a dissecting microscope (StereoZoom 6 Photo; Leica Microsystems GmbH, Wetzlar, Germany) and placed on a separate, clean slide with a drop of modified carbol fuchsin stain (Carr and Walker, 1961; Kao, 1975). A coverslip was placed over the droplet of stain containing the excised root tip and a clean sheet of bibulous paper was placed over the slide while gently applying pressure with a pencil eraser. An average of 10 highly resolved cells per specimen were used to visualize the total number of chromosomes using a light microscope (Eclipse 80i, Nikon, Melville, NY). Extended depth of field was achieved by layered images containing multiple focal points using Photoshop CS4 (Adobe Systems, San Jose, CA).

Results and Discussion

Liriope exiliflora.

The relatively large 2C genome size of L. exiliflora ranged from 24.89 to 26.18 pg (Table 2). This range of genome size fell between that of L. gigantea and L. muscari. Cytology determined L. exiliflora (MCI 2011-100) to be a hexaploid at 2n = 6x = 108 (Fig. 1A). Possibly, former cytological studies included L. exiliflora under a different synonym, although no former studies were found to compare with our findings. Our results lend evidence for the treatment of L. exiliflora as a separate species in agreement with Fantz (2008b) and in contrast to claims of synonymy with L. muscari by Nesom (2010). Cultivars Silver Dragon and Quail Garden were acquired as L. spicata and were reassigned L. exiliflora according to Fantz (2008b). However, further investigation into a close relationship between L. exiliflora and L. spicata may be warranted based on their similar morphology, ploidy, and monoploid genome size values (Table 3).

Fig. 1.
Fig. 1.

Representative photomicrographs of metaphase chromosomes from root tip cell of liriopogons viewed at ×1000: (A) Liriope exiliflora (2n = 6x = 108); (B) L. minor (2n = 2x = 36); (C) Ophiopogon japonicus var. caespitosa ‘Seoulitary Man’ (2n = 4x = 72).

Citation: HortScience horts 49, 2; 10.21273/HORTSCI.49.2.145

Table 3.

Monoploid (1Cx) genome sizes of cultivated Liriope and Ophiopogon determined using flow cytometry and grouped by genus and species.

Table 3.

Liriope gigantea.

Often confused with L. muscari, four cultivars of L. gigantea including ‘Green Giant’, ‘Evergreen Giant’, ‘Lynn Lowrey’, and ‘Merton Jacobs’ were found to have larger 2C genome sizes (26.23 to 28.86 pg) than any L. muscari (17.64 to 21.53 pg) included in this study (Table 2). Cytology determined L. gigantea (MCI 2011-099) to be a tetraploid at 2n = 4x = 72. Monoploid genome sizes were significantly larger in L. gigantea (6.92 pg) than L. muscari (4.76 pg). Former cytological studies possibly included L. gigantea under a different synonym, although no former studies were found to compare with our findings. Cultivars Green Giant, Evergreen Giant, and Lynn Lowrey were acquired as L. muscari. However, these cultivars were reassigned according to Fantz (2008b) and Nesom (2010) and based on similarity of genome size and ploidy level with known L. gigantea.

Liriope graminifolia.

This grass-like species of Liriope is characterized by thin, soft leaves with heavy flowering inflorescences hidden among or just topping the leaves (Chen and Tamura, 2000a). Liriope matching this description in the present study included ‘Porcupine’, a clone (MCI 2010-063) early-blooming in April in North Carolina, and a wild-collected clone (MCI 2012-098) from Sichuan, China (D. Probst, personal communication). Although the leaf form was similar for all specimens in this group, inflorescence length varied. Some specimens exhibited flowers blooming well above the foliage (initially thought to be a narrow leaf form of L. platyphylla) and some specimens exhibited flowers blooming among the foliage. The 2C genome size for L. graminifolia ranged from 10.44 to 11.08 pg (Table 2) and cytology determined L. graminifolia Clone B (MCI 2012-098) and L. graminifolia ‘Porcupine’ (MCI 2010-056) to be a diploids with 2n = 2x = 36. Monoploid genome sizes for L. graminifolia (5.41 pg) did not significantly differ from the morphologically similar diploid, L. minor (5.60 pg) (Table 3). In addition to diploids, previous research has reported L. graminifolia to be tetraploid (2n = 72) and hexaploid (2n = 108) (Table 1). Liriope graminifolia Clone B was acquired as O. intermedius and reassigned according to Chen and Tamura (2000a) and Nesom (2010).

Liriope longipedicellata.

As the name suggests, the most identifiable feature of L. longipedicellata is its extended pedicels (Chen and Tamura, 2000a), giving the inflorescence a bottle brush appearance. Otherwise, the species resembles the narrow-leaved L. graminifolia, and similar genome sizes and ploidy levels further suggest a close relationship. Liriope longipedicellata ‘Grape Fizz’ was found to have a 2C genome size of 11.10 pg and the wild-collected L. longipedicellata (MCI 2012-092) was found to have a 2C genome size 12.31 pg, just outside the observed range for L. graminifolia (Table 2). Cytology demonstrated L. longipedicellata (MCI 2012-092) to be a diploid with 2n = 2x = 36. Monoploid genome sizes for L. longipedicellata (5.86 pg) were found to be similar to L. minor (5.60 pg) but larger than L. graminifolia (5.41 pg), all being narrow leaf liriopes (Table 3). Although it is possible that former cytological studies included L. longipedicellata under a different synonym, no former studies were found to compare with our findings. Liriope longipedicellata ‘Grape Fizz’ was acquired as O. intermedius ‘Grape Fizz’ and was reassigned according to Chen and Tamura (2000a).

Liriope minor.

This species represents a spreading, dwarf Liriope with narrow leaves occasionally blotched yellow with leaf and inflorescence length less than 20 cm (Chen and Tamura, 2000a; Fantz, 2008b). Both specimens in this study exhibited yellow blotched variegation. Cytometry revealed 2C genome sizes from 11.08 to 11.31 pg (Table 2), placing it in a similar range as L. graminifolia and L. longipedicellata. Further cytological examination of both specimens revealed L. minor to be a diploid 2n = 2x = 36 (Fig. 1B), concurring with previous studies reporting L. minor also to be a diploid (Table 1). The similar appearance, genome sizes, and ploidy levels revealed in this study suggest a close relationship among L. graminifolia, L. longipedicellata, and L. minor with L. minor having the smallest stature. Liriope minor ‘Torafu’ was acquired as L. muscari ‘Torafu’ and reassigned according to Chen and Tamura (2000a) and Fantz (2008b).

Liriope muscari.

Seventeen cultivars of L. muscari ranged in 2C genome size from 17.64 to 21.53 pg (Table 2). Cultivars with large genome sizes such as ‘Superba’ (21.53 pg) and ‘Big Blue’ (21.40 pg) were observed to have the most vigor (fastest growth and largest clumps) and heaviest fruit set of all L. muscari tested (J. Lattier, personal observation). A possible explanation for this is suggested in an earlier study by Westfall (1950) where many L. muscari studied were found to be sterile or only partially fertile as a result of high levels of aneuploidy. In addition, hypotetraploid lines were found to have high levels of variation in inflorescence morphology, leaf width, vigor, and fertility (Westfall, 1950). Our results indicate a similar trend with all green leaf forms (except for the white-flowering ‘Monroe White’) having a 2C genome size greater than 20 pg and all variegated forms or forms with abnormal inflorescences having a 2C genome size less than 20 pg (Table 2). Monoploid genome sizes for L. muscari (4.76 pg) indicated a unique genome size within Liriope, with the exception of L. platyphylla which had a similar genome size of (5.03 pg) (Table 3). Cytology of ‘Silvery Sunproof’ confirmed it to be a tetraploid with 2n = 4x = 72, contrasting with one report of a diploid at 2n = 36 and one report of a rare specimen at 2n = 112 for L. muscari (Table 1).

Liriope platyphylla.

Recent taxonomic studies including Nesom (2010) have treated the broad-leaved L. platyphylla as synonymous with L. muscari, or a variety of L. muscari, based on the merger of these two species by Hara (1984) and Hsu and Li (1981). Also, molecular studies have indicated a close relationship between L. muscari and L. platyphylla (Wu et al., 1998). However, the combination of the two species has led to much confusion in interpretation of previous literature and identification of this distinctive Liriope (Fantz, 2008b). Samples in the present study were distinguishable easily from L. muscari in agreement with Fantz (2008b) based on their wide, leathery leaves and elongated inflorescence extending well above the foliage. Eight specimens were tested including one with a branching rachis (MCI 2012-095), one particularly large form from the Atlanta Botanical Garden with a nearly 4-foot tall inflorescence (MCI 2012-125) and one cultivar (Korean Giant). Flow cytometry revealed a ploidy series including four specimens with genome sizes from 10.02 to 10.71 pg and four specimens with 2C genome sizes from 19.04 to 19.95 pg (Table 2). Although morphologically distinct, 1Cx values of L. platyphylla (5.03 pg) were similar to L. muscari (4.76 pg) (Table 3). There was a general trend of the tetraploid specimens exhibiting more vigorous growth and larger overall sizes. A further cytological study was conducted finding MCI 2010-019 to be a diploid with 2n = 2x = 36, whereas MCI 2010-051 was found to be a tetraploid with 2n = 4x = 72. The only other reported ploidy level for L. platyphylla was found to be hexaploid with 2n = 108, although it is likely that cytological studies have been conducted under different synonyms (Table 1).

Liriope spicata.

The relatively large 2C genome size of L. spicata ranged from 23.85 to 23.91 pg but was slightly lower than L. exiliflora. Monoploid genome sizes for L. spicata (3.99 pg) and L. exiliflora (4.27 pg) were not significantly different (Table 3). Cytology determined L. spicata (JCRA S07) to be a hexaploid at 2n = 6x = 108. In addition to hexaploids, previous research has reported many different ploidy levels for L. spicata including (2n = 45, 72, 88, 90) (Table 1). This species represents a diminutive Liriope, which spreads aggressively by rhizomes (Fantz, 2008b). This species is often confused in the trade with the larger L. exiliflora, which clumps for several years before spreading, although less aggressively than L. spicata (Fantz, 2008b).

Ophiopogon intermedius.

Cytometric analysis of ‘Aztec’, ‘Twisted Variegated’, and two samples of ‘Variegatus’ showed a range of 2C genome sizes from 11.10 to 11.21 pg (Table 2). Cytology determined ‘Aztec’ to be a diploid with 2n = 2x = 36. However, previous studies have reported wide ranges of ploidy levels for O. intermedius at 2n = 36, 68, 72, 108, and 112 (Table 1). Ophiopogon intermedius ‘Aztec’ was acquired as L. spicata ‘Aztec’ and was reassigned in agreement with Fantz (2009) and Nesom (2010). Ophiopogon intermedius ‘Aztec’ is misidentified commonly in the trade as L. muscari or O. jaburan (Fantz, 2009).

Ophiopogon jaburan.

Cytometry of O. jaburan ‘HOCF’, ‘Crystal Fan’, ‘Vittatus’, ‘Ursala’s Blue Fruit’, and ‘Wuhan Variegated’ found a range of 2C genome sizes from 16.08 to 16.49 pg (Table 2). Cytology of ‘Crystal Fan’ documented it to be a diploid with 2n = 2x = 36. Interestingly, O. jaburan had a significantly larger monoploid genome size (8.15 pg) than all other liriopogons (Table 3). Compared with other liriopogons in this study, O. jaburan had a surprisingly consistent cytological record of existing primarily as a diploid at 2n = 36 (Table 1) in agreement with our findings.

Ophiopogon japonicus.

Cytometry of 11 taxa of O. japonicus showed two distinct ranges of 2C genome sizes. The majority of O. japonicus samples ranged from 20.39 to 22.04 pg, whereas ‘Tears of Gold’ and ‘Seoulitary Man’ ranged from 25.24 to 25.44 pg (Table 2). These two clones represented varieties with larger overall form and were found to have a significantly different 1Cx value (6.34 pg) than the other O. japonicus (5.27 pg) (Table 3). Originally thought to be a hyperploid specimen, cytology confirmed ‘Seoulitary Man’ to be a tetraploid with 2n = 4x = 72 (Fig. 1C). Ploidy analysis remains inconclusive for other O. japonicus, likely as a result of high levels of hypotetraploidy as reported in previous studies (Table 1). A wide range of ploidy levels has been previously reported for O. japonicus including 2n = 36, 67, 68, 70, and 72 (Table 1). In the present study, three samples examined using flow cytometry (‘Fiuri Gyoku Ryu’, ‘Tama Ryu Nishiki’, and ‘Variegatus’) yielded multiple fluorescence peaks with hypotetraploid peaks being associated with the variegated tissue. This phenomenon was only observed in variegated cultivars of O. japonicus. Wang and Xu (1990) also found cytochimeras in O. japonicus with diploid, triploid, and tetraploid cells existing in the same plant.

Ophiopogon planiscapus.

Of the eight taxa of O. planiscapus tested, 2C genome sizes ranged from 12.15 to 12.66 pg (Table 2). With the exception of the few large varieties of O. japonicus included in this study, O. planiscapus had a significantly different 1Cx value (6.22 pg) among the liriopogons. Cytology of the cultivar Nigrescens showed it to be 2n = 2x = 36. The majority of former cytological studies of O. planiscapus agrees with the present study; however, tetraploid forms (2n = 72) have been reported (Table 1).

Ophiopogon umbraticola.

Often mislabeled as O. chingii in the nursery industry (J. Lattier, personal observation), two samples of O. umbraticola (MCI 2010-059, JCRA 990336) had 2C genome sizes ranging from 14.41 to 14.45 pg, which represents a unique range of genome size compared with all liriopogons tested in the present study (Table 2). Further cytological study of O. umbraticola (MCI 2010-059) revealed it to be a diploid at 2n = 2x = 36 in contrast to one previous report of hypotetraploidy, 2n = 68 (Table 1). Monoploid genome sizes for O. umbraticola (7.22 pg) were significantly different from the rest of the Ophiopogon (Table 3). Ophiopogon umbraticola (MCI 2010-059) was acquired as O. chingii and reassigned according to Chen and Tamura (2000b) and Tanaka (2001a).

Information on ploidy levels and genome sizes can have important implications for plant breeding (Ranney, 2006). Intraploid hybridizations are often more productive than interploid hybridizations, although interploid hybridizations can often provide an avenue for developing seedless cultivars. Also, compatibility of genomes/chromosomes is necessary for meiosis to function properly, and similarity in genome sizes can be indicative of close phylogenetic relationships and genome compatibility within taxonomic groups. Development of fertile hybrids may be improved when breeding among plants with similar genome sizes and ploidy levels (Parris et al., 2010).

This study details the development and documentation of an extensive collection of both living specimens and herbarium vouchers for liriopogons. Several source names were misidentified to genus, and many were misidentified to species like in a previous report by Fantz (1994). Genome sizes and ploidy levels were determined for all taxa in this study. Results confirm the basic chromosome number of x = 18 for liriopogons with aneuploidy, polyploidy, and cytochimeras found in some cases. Based on our sampling, Liriope examined fit into three ploidy groups with one exception of a ploidy series of L. platyphylla. The diploid group consisted of L. graminifolia, L. longipedicellata, L. minor, and some L. platyphylla. The tetraploid group consisted of L. muscari and the remaining L. platyphylla. The hexaploid group consisted of L. exiliflora and L. spicata. Although controversy surrounds the maintenance of L. gigantea, L. graminifolia, and L. exiliflora as separate species, differences in 1Cx genome size lends evidence for maintaining L. gigantea as a distinct species separate from L. muscari and as suggested by Fantz (2008b) and Nesom (2010), L. muscari as a distinct species separate from L. exiliflora or L. spicata as suggested by Fantz (2008b), and L. graminifolia as a distinct species separate from L. spicata or L. exiliflora as suggested by Chen and Tamura (2000a) and Nesom (2010). Ophiopogon included in this study formed two ploidy groups. The diploid group included O. intermedius, O. jaburan, O. planiscapus, and O. umbraticola. The tetraploid/hypotetraploid group consisted of O. japonicus. Monoploid genome sizes varied based on genus and species and ranged from 4.27 pg in L. exiliflora to 8.15 pg in O. jaburan (Table 3). Based on the taxa sampled, mean 1Cx genome sizes were smaller for Liriope (5.10 pg) than for Ophiopogon (6.27 pg) (Table 3). Although breeding efforts in the past have been limited by confusion over proper identification of germplasm and lack of information on ploidy levels and cytogenetics of available clones and cultivars, the reference collection established in this study will aid future revisions as well as assist in the development of breeding strategies for liriopogons.

Literature Cited

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  • Broussard, M.C. 2007 A horticultural study of Liriope and Ophiopogon: Nomenclature, morphology, and culture. PhD diss.,, Louisiana State University, Baton Rouge, LA

  • Cao, Y., Qiao, D.-r., Li, Y.-x., Xing, H.-x. & Jiang, Y. 2002 Karyotypical analysis of erective and creepy Ophiopogon japonicus in Mianyang of Sichuan Journal of Sichuan University 39 345 348 (Natural Science Edition

    • Search Google Scholar
    • Export Citation
  • Carr, D.H. & Walker, J.E. 1961 Carbol fuchsin as a stain for human chromosomes Stain Technol. 36 233 236

  • Chen, S.C. & Tamura, M.N. 2000a Liriope, p. 250–251. In: Wu, Z.Y. and P. H. Raven (eds.). Flora of China 24. Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis, MO

  • Chen, S.C. & Tamura, M.N. 2000b Ophiopogon, p. 250–251. In: Wu, Z.Y. and P. H. Raven (eds.). Flora of China 24. Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis, MO

  • Cheng, Z.H., Wu, T., Guo, Y.L., Yu, B.Y. & Xu, L.S. 2006 Two new steroidal glycosides from Liriope muscari Chin. Chem. Lett. 17 31 34

  • Conran, J.G. & Tamura, M.N. 1998 Convallariaceae, p. 186–198. In: Kubitzki, K. (ed.). The families and genera of vascular plants. Springer, Berlin, Germany

  • Cutler, D.F. 1992 Vegetative anatomy of Ophiopogoneae (Convallariaceae) Bot. J. Linn. Soc. 110 385 419

  • Denda, T., Nakamura, K. & Yokota, M. 2006 Karyotype of Ophiopogon reversus (Convallariaceae) from Taiwan and the southern Ryukyus Taiwania 51 117 122

  • Dudgeon, W. 1923 Section of botany. Proc. of the 9th Indian Science Congress. Proc. Asiat. Soc. Bengal 18:95–124

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  • Fantz, P.R. 1994 Taxonomic problems in cultivated liriopogons HortTechnology 3 146 150

  • Fantz, P.R. 2008a Macrophytogeography of cultivated liriopogons and genera delineation HortTechnology 18 334 342

  • Fantz, P.R. 2008b Species of Liriope cultivated in the southeastern United States HortTechnology 18 343 348

  • Fantz, P.R. 2009 Names and species of Ophiopogon cultivated in the southeastern United States HortTechnology 19 385 394

  • Fu, C.X. & Hong, D.Y. 1989 Cytotaxonomical studies on Liliaceae (S.1.); (2) Report on chromosome numbers and karyotypes of 8 species of 8 genera from Zhejiang, China Acta Phytotaxon. Sin. 27 439 450

    • Search Google Scholar
    • Export Citation
  • Fukai, S., Shimomura, T. & Kondo, T. 2008 Convallariaceae ground cover plants native to Asia. ISHS Acta Horticulturae 769: XXVII International Horticultural Congress—IHC2006: International Symposium on Asian plants with unique horticultural potential

  • Ge, C., Li, Y. & Zhou, Y. 1987 Observations on the chromosome numbers of medicinal plants plants of Shandong province Acta Botanica Yunnanica 9 333 338

    • Search Google Scholar
    • Export Citation
  • Hara, H. 1984 Comments on the East Asiatic plants (13) J. Jap. Bot. 59 33 41

  • Hasegawa, K.M. 1968 Cytotaxonomic studies on the genera Liriope and Ophiopogon in Japan J. Japanese Bot. 43 141 155

  • Hsu, C.C. 1971 Preliminary chromosome studies on the vascular plants of Taiwan (IV). Counts and some systematic notes on some monocotyledons Taiwania 16 123 136

    • Search Google Scholar
    • Export Citation
  • Hsu, P.S. & Li, L.C. 1981 Critical notes on the classification of the Liriope muscari complex Acta Phytotax. Sini. 19 456 461

  • Hume, H.H. 1961 The OphiopogonLiriope complex Baileya 9 135 158

  • Kao, K.N. 1975 A nuclear staining method for protoplasts, p. 60–64. In: Gamborg, O.L. and L.Z. Wetter (eds.). Plant tissue culture methods. L.R. National Research Council of Canada, Praire Regional Laboratory, Saskatoon, Saskatchewan, Canada

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    • Search Google Scholar
    • Export Citation
  • Ko, S.C., Kim, Y.O. & Kim, Y.S. 1985 A cytotaxonomical study on the tribe Ophiopogoneae in Korea Kor. J. Plant Tax. 15 111 125

  • Kondo, K., Taniguchi, K., Tanaka, R. & Gu, Z. 1992 Karyomorphological studies in Chinese plant-species involving the Japanese floristic elements, I. American Camellia Yearbook. p. 131–156

  • Larsen, K. 1963 Studies in the flora of Thailand (IV). Counts and some systematic notes on some monocotyledons Taiwania 16 123 136

  • Li, G., Ra, W.-H., Park, J.-W., Kwon, S.-W., Lee, J.-H., Park, C.-B. & Park, Y.-J. 2011 Developing EST-SSR markers to study molecular diversity in Liriope and Ophiopogon Biochem. Syst. Ecol. 39 241 252

    • Search Google Scholar
    • Export Citation
  • Liang, G., Yang, M. & Yan, Y. 1998 Karyotypical analysis of Ophiopogon japonicus in Sichuan Journal of Southwest Agricultural University 20 307 310

  • Liu, W.-Q., Jin, J.-H. & Liao, W.-B. 2007 Ophiopogon acerobracteatus (Convallariaceae), a new species from southern China Ann. Bot. Fenn. 44 492 494

  • Liu, Y., Zhang, S.A., Hsu, P.S. & Li, L.C. 1985 Chromsome numbers of several cultivated plants from Shanghai J. Wuhan Bot. Res. 3 225 228 (Wuhan Zhiwuxue Yanjou)

    • Search Google Scholar
    • Export Citation
  • Malik, C.P. 1961 Chromosome number in some Indian Angiosperms: Monocotyledons Sci. Cult. 27 197 198

  • Matsuura, H. & Suto, T. 1935 Contributions to the idiogram study in phanerogamous plants. I J. Fac. Sci. Hokkaido Imp. Univ., Ser. 5. Bot. 5 33 75

  • Mcharo, M., Bush, E., LaBonte, D., Broussard, C. & Urbatsch, L. 2003 Molecular and morphological investigation of ornamental liriopogons J. Amer. Soc. Hort. Sci. 128 575 577

    • Search Google Scholar
    • Export Citation
  • Nagamatsu, T. & Noda, S. 1964 Chromsome constitution of Ophiopogon japonicus Bull. Osaka Gakuin Univ 3 185 190 [in Japanese with English summary]

  • Nagamatsu, T. & Noda, S. 1971 Balanced hypotetraploids in Ophiopogon japonicus and O. ohwii Cytologia (Tokyo) 36 332 340

  • Nesom, G.L. 2010 Overview of Liriope and Ophiopogon (Ruscaceae) naturalized and commonly cultivated in the USA Phytoneuron 56 1 31

  • Oinuma, T. 1944 Chromosome number of Ophiopogon planiscapus Nakai Jap. J. Genet. 20 130 131 [in Japanese]

  • Oinuma, T. 1946 Karyotype analysis of Liriope and Ophiopogon La Kromosomo 2 71 75 [in Japanese with English summary]

  • Oinuma, T. 1949 Further studies on chromosomes of Ophiopogonaceae Jap. J. Genet. Suppl. 2 29 34 [in Japanese with English résumé]

  • Parris, J.K., Ranney, T.G., Knap, H.T. & Baird, W.V. 2010 Ploidy levels, relative genome sizes, and base pair composition in magnolia J. Amer. Soc. Hort. Sci. 135 533 547

    • Search Google Scholar
    • Export Citation
  • Ranney, T.G. 2006 Polyploidy: From evolution to new plant development Proc. Intern. Plant Propagators' Soc. 56 604 607

  • Roy, S.C., Ghosh, S. & Chatterjee, A. 1988 A cytological survey of eastern Himalayan plants. II Cell Chromosome Res. 11 93 97

  • Rudall, P. 2000 Systematics of Ruscaceae/Convallariaceae: A combined morphological and molecular investigation Bot. J. Linn. Soc. 134 73 92

  • Sarkar, A.K., Datta, R. & Raychowdhury, M. 1974 In IOPB chromosome number reports XLVI Taxon 23 801 812

  • Sato, D. 1942 Karyotype alteration and phylogeny in Liliaceae and allied families J. Jpn. Bot. 12 57 161

  • Sen, S. 1973 Structural hybridity intra- and interspecific levels in Lilliales Folia Biol. (Cracow) 21 183 197

  • Sharma, A.K. & Chaudhuri, M. 1964 Cytological studies as an aid in assessing the status of Sanseviera, Ophiopogon, and Curculigo Nucleus 7 43 58

  • Sheriff, A. & Singh, B.K.S. 1975 Hexaploid wild populations of Ophiopogon intermedium from Shiradi Ghats, Karnataka State. Proc. Indian Sci. Congr. Assoc. 62:117

  • Skinner, H.T. 1971 Some liriopogon comments J. Royal Hort. Soc. 96 345 350

  • Tamura, M.N. 1990 Studies on the genus Ophiopogon (Liliaceae) of Phu Kradung in Thailand Acta Phytotax. Geobot. 41 1 6

  • Tanaka, N. 2000 Taxonomic notes on Ophiopogon of South Asia VII J. Jpn. Bot. 75 191 212

  • Tanaka, N. 2001a Taxonomic notes on Ophiopogon (Convallariaceae) of East Asia (I) J. J. Bot. 76 59 76

  • Tanaka, N. 2001b Taxonomic notes on Ophiopogon (Convallariaceae) of East Asia (II) J. Jpn. Bot. 76 151 165

  • Tanaka, N. 2001c Taxonomic notes on Ophiopogon (Convallariaceae) of East Asia (III) J. Jpn. Bot. 76 205 218

  • Terasaka, O. & Tanaka, R. 1974 Cytological studies on the nuclear differentiation in microspore division of some angiosperms Bot. Mag. Tokyo 87 209 217

    • Search Google Scholar
    • Export Citation
  • Thunberg, C.P. 1780 Convallaria japonica November Act. Reg. Soc. Upsala 3 208

  • Trueblood, C.E. 2009 An estimate of the commercial value of potentially invasive nursery crops grown in North Carolina, p. 63–75. In: An Invasive Species Assessment System for the North Carolina Horticultural Industry. MS thesis, North Carolina State University, Raleigh, NC

  • Wang, G., Meng, Y. & Yang, Y. 2013 Karyological analyses of 33 species of the tribe Ophiopogoneae (Liliaceae) from Southwest China J. Plant Res. 126 597 604

    • Search Google Scholar
    • Export Citation
  • Wang, K.W., Ju, X.Y., Zhang, L., Wang, W. & Shen, L.Q. 2012 A novel C27-steroidal glycoside sulfate from Liriope graminifolia Yao Xue Xue Bao 47 619 623

  • Wang, S.-F. & Xu, J.-M. 1990 Report on karyotypes of Smilacina tatsienensis and Ophiopogon japonicus Acta Phytotaxonomica Sinica 28 207 210

  • Westfall, J.J. 1950 Aneuploidy in Liriope muscari Bailey Amer. J. Bot. 37 667

  • Wu, T., Wang, Y. & Yu, B. 1998 Classification of four species of plant genus Liriope (Liriope Lour.) using RAPD Chin. Tradit. Herbal Drugs 29 37 40

  • Yamashita, J. & Tamura, M.N. 2001 Karyotype analysis of six species of the genus Ophiopogon (Convallariaceae-Ophiopogoneae) J. Jpn. Bot. 76 100 119

    • Search Google Scholar
    • Export Citation
  • Yang, Y.-P., Li, H., Liu, X.-Z. & Kondo, K. 1990 Karyotype study on the genus Ophiopogon in Yunnan Acta Bot. Yunnan. Suppl. 3 94 102 [in Chinese with English abstract]

    • Search Google Scholar
    • Export Citation
  • Yu, B.-Y., Qiu, S.-X., Zaw, K., Xu, G.-J., Hirai, Y., Shoji, J., Fong, H.S. & Douglas, A. 1996 Steroidal glycosides from the subterranean parts of Liriope spicata var. prolifera Phytochem. 43 201 206

    • Search Google Scholar
    • Export Citation
  • Zhang, D.M. 1998 Systematics of tribe Ophiopogoneae (Liliaceae s.l.) with special reference to karyotypes and chromosomal evolution Cathaya 10 1 154

    • Search Google Scholar
    • Export Citation
  • Zhou, Q., Zhou, J., Chen, J. & Wang, X. 2009 Karyotype analysis of medicinal plant Liriope spicata var. prolific Biologia 64 680 683

If the inline PDF is not rendering correctly, you can download the PDF file here.

Contributor Notes

This research was funded, in part, by the North Carolina Agricultural Research Service (NCARS), Raleigh, NC.

Use of trade names in this publication does not imply endorsement by the NCARS of products named nor criticism of similar ones not mentioned.

We gratefully acknowledge Mark Weathington, JC Raulston Arboretum, Raleigh, NC; Alexander Krings, North Carolina State University Herbarium, Raleigh, NC; Tony Avent, Dennis Carey, and Jeremy Schmidt, Plant Delights Nursery, Raleigh, NC; Darrell Probst, Garden Vision Epimediums, Hubbardston, MA; Ron Rabideau, RareFind Nursery, Jackson, NJ; Paul Jones, Sarah P. Duke Gardens, Durham, NC; and Nathan Lynch and Kim Shearer, Mountain Crop Improvement Lab, Mills River, NC, for their cooperation, technical assistance, and contributions of plant material for this study.

From a thesis submitted by J.D.L. in partial fulfillment of the requirements for the MS degree.

Graduate Research Assistant.

Professor Emeritus and Research Taxonomist.

Professor.

Owner of Plant Delights Nursery and founder of Juniper Level Botanical Gardens.

To whom reprint requests should be addressed; e-mail tom_ranney@ncsu.edu.

  • View in gallery

    Representative photomicrographs of metaphase chromosomes from root tip cell of liriopogons viewed at ×1000: (A) Liriope exiliflora (2n = 6x = 108); (B) L. minor (2n = 2x = 36); (C) Ophiopogon japonicus var. caespitosa ‘Seoulitary Man’ (2n = 4x = 72).

  • Bailey, L.H. 1929 The case of Ophiopogon and Liriope Gentes Herb. 2 1 37

  • Broussard, M.C. 2007 A horticultural study of Liriope and Ophiopogon: Nomenclature, morphology, and culture. PhD diss.,, Louisiana State University, Baton Rouge, LA

  • Cao, Y., Qiao, D.-r., Li, Y.-x., Xing, H.-x. & Jiang, Y. 2002 Karyotypical analysis of erective and creepy Ophiopogon japonicus in Mianyang of Sichuan Journal of Sichuan University 39 345 348 (Natural Science Edition

    • Search Google Scholar
    • Export Citation
  • Carr, D.H. & Walker, J.E. 1961 Carbol fuchsin as a stain for human chromosomes Stain Technol. 36 233 236

  • Chen, S.C. & Tamura, M.N. 2000a Liriope, p. 250–251. In: Wu, Z.Y. and P. H. Raven (eds.). Flora of China 24. Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis, MO

  • Chen, S.C. & Tamura, M.N. 2000b Ophiopogon, p. 250–251. In: Wu, Z.Y. and P. H. Raven (eds.). Flora of China 24. Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis, MO

  • Cheng, Z.H., Wu, T., Guo, Y.L., Yu, B.Y. & Xu, L.S. 2006 Two new steroidal glycosides from Liriope muscari Chin. Chem. Lett. 17 31 34

  • Conran, J.G. & Tamura, M.N. 1998 Convallariaceae, p. 186–198. In: Kubitzki, K. (ed.). The families and genera of vascular plants. Springer, Berlin, Germany

  • Cutler, D.F. 1992 Vegetative anatomy of Ophiopogoneae (Convallariaceae) Bot. J. Linn. Soc. 110 385 419

  • Denda, T., Nakamura, K. & Yokota, M. 2006 Karyotype of Ophiopogon reversus (Convallariaceae) from Taiwan and the southern Ryukyus Taiwania 51 117 122

  • Dudgeon, W. 1923 Section of botany. Proc. of the 9th Indian Science Congress. Proc. Asiat. Soc. Bengal 18:95–124

  • Fantz, P.R. 1993 Taxonomic problems in cultivated liriopogons HortTechnology 3 146 149

  • Fantz, P.R. 1994 Taxonomic problems in cultivated liriopogons HortTechnology 3 146 150

  • Fantz, P.R. 2008a Macrophytogeography of cultivated liriopogons and genera delineation HortTechnology 18 334 342

  • Fantz, P.R. 2008b Species of Liriope cultivated in the southeastern United States HortTechnology 18 343 348

  • Fantz, P.R. 2009 Names and species of Ophiopogon cultivated in the southeastern United States HortTechnology 19 385 394

  • Fu, C.X. & Hong, D.Y. 1989 Cytotaxonomical studies on Liliaceae (S.1.); (2) Report on chromosome numbers and karyotypes of 8 species of 8 genera from Zhejiang, China Acta Phytotaxon. Sin. 27 439 450

    • Search Google Scholar
    • Export Citation
  • Fukai, S., Shimomura, T. & Kondo, T. 2008 Convallariaceae ground cover plants native to Asia. ISHS Acta Horticulturae 769: XXVII International Horticultural Congress—IHC2006: International Symposium on Asian plants with unique horticultural potential

  • Ge, C., Li, Y. & Zhou, Y. 1987 Observations on the chromosome numbers of medicinal plants plants of Shandong province Acta Botanica Yunnanica 9 333 338

    • Search Google Scholar
    • Export Citation
  • Hara, H. 1984 Comments on the East Asiatic plants (13) J. Jap. Bot. 59 33 41

  • Hasegawa, K.M. 1968 Cytotaxonomic studies on the genera Liriope and Ophiopogon in Japan J. Japanese Bot. 43 141 155

  • Hsu, C.C. 1971 Preliminary chromosome studies on the vascular plants of Taiwan (IV). Counts and some systematic notes on some monocotyledons Taiwania 16 123 136

    • Search Google Scholar
    • Export Citation
  • Hsu, P.S. & Li, L.C. 1981 Critical notes on the classification of the Liriope muscari complex Acta Phytotax. Sini. 19 456 461

  • Hume, H.H. 1961 The OphiopogonLiriope complex Baileya 9 135 158

  • Kao, K.N. 1975 A nuclear staining method for protoplasts, p. 60–64. In: Gamborg, O.L. and L.Z. Wetter (eds.). Plant tissue culture methods. L.R. National Research Council of Canada, Praire Regional Laboratory, Saskatoon, Saskatchewan, Canada

  • Kim, J.-H., Kim, D.-K., Forest, F., Fay, M.F. & Chase, M.W. 2010 Molecular phylogenetics of Ruscaceae sensu lato and related families (Asparagales) based on plastid and nuclear DNA sequences Ann. Bot. (Lond.) 106 775 790

    • Search Google Scholar
    • Export Citation
  • Ko, S.C., Kim, Y.O. & Kim, Y.S. 1985 A cytotaxonomical study on the tribe Ophiopogoneae in Korea Kor. J. Plant Tax. 15 111 125

  • Kondo, K., Taniguchi, K., Tanaka, R. & Gu, Z. 1992 Karyomorphological studies in Chinese plant-species involving the Japanese floristic elements, I. American Camellia Yearbook. p. 131–156

  • Larsen, K. 1963 Studies in the flora of Thailand (IV). Counts and some systematic notes on some monocotyledons Taiwania 16 123 136

  • Li, G., Ra, W.-H., Park, J.-W., Kwon, S.-W., Lee, J.-H., Park, C.-B. & Park, Y.-J. 2011 Developing EST-SSR markers to study molecular diversity in Liriope and Ophiopogon Biochem. Syst. Ecol. 39 241 252

    • Search Google Scholar
    • Export Citation
  • Liang, G., Yang, M. & Yan, Y. 1998 Karyotypical analysis of Ophiopogon japonicus in Sichuan Journal of Southwest Agricultural University 20 307 310

  • Liu, W.-Q., Jin, J.-H. & Liao, W.-B. 2007 Ophiopogon acerobracteatus (Convallariaceae), a new species from southern China Ann. Bot. Fenn. 44 492 494

  • Liu, Y., Zhang, S.A., Hsu, P.S. & Li, L.C. 1985 Chromsome numbers of several cultivated plants from Shanghai J. Wuhan Bot. Res. 3 225 228 (Wuhan Zhiwuxue Yanjou)

    • Search Google Scholar
    • Export Citation
  • Malik, C.P. 1961 Chromosome number in some Indian Angiosperms: Monocotyledons Sci. Cult. 27 197 198

  • Matsuura, H. & Suto, T. 1935 Contributions to the idiogram study in phanerogamous plants. I J. Fac. Sci. Hokkaido Imp. Univ., Ser. 5. Bot. 5 33 75

  • Mcharo, M., Bush, E., LaBonte, D., Broussard, C. & Urbatsch, L. 2003 Molecular and morphological investigation of ornamental liriopogons J. Amer. Soc. Hort. Sci. 128 575 577

    • Search Google Scholar
    • Export Citation
  • Nagamatsu, T. & Noda, S. 1964 Chromsome constitution of Ophiopogon japonicus Bull. Osaka Gakuin Univ 3 185 190 [in Japanese with English summary]

  • Nagamatsu, T. & Noda, S. 1971 Balanced hypotetraploids in Ophiopogon japonicus and O. ohwii Cytologia (Tokyo) 36 332 340

  • Nesom, G.L. 2010 Overview of Liriope and Ophiopogon (Ruscaceae) naturalized and commonly cultivated in the USA Phytoneuron 56 1 31

  • Oinuma, T. 1944 Chromosome number of Ophiopogon planiscapus Nakai Jap. J. Genet. 20 130 131 [in Japanese]

  • Oinuma, T. 1946 Karyotype analysis of Liriope and Ophiopogon La Kromosomo 2 71 75 [in Japanese with English summary]

  • Oinuma, T. 1949 Further studies on chromosomes of Ophiopogonaceae Jap. J. Genet. Suppl. 2 29 34 [in Japanese with English résumé]

  • Parris, J.K., Ranney, T.G., Knap, H.T. & Baird, W.V. 2010 Ploidy levels, relative genome sizes, and base pair composition in magnolia J. Amer. Soc. Hort. Sci. 135 533 547

    • Search Google Scholar
    • Export Citation
  • Ranney, T.G. 2006 Polyploidy: From evolution to new plant development Proc. Intern. Plant Propagators' Soc. 56 604 607

  • Roy, S.C., Ghosh, S. & Chatterjee, A. 1988 A cytological survey of eastern Himalayan plants. II Cell Chromosome Res. 11 93 97

  • Rudall, P. 2000 Systematics of Ruscaceae/Convallariaceae: A combined morphological and molecular investigation Bot. J. Linn. Soc. 134 73 92

  • Sarkar, A.K., Datta, R. & Raychowdhury, M. 1974 In IOPB chromosome number reports XLVI Taxon 23 801 812

  • Sato, D. 1942 Karyotype alteration and phylogeny in Liliaceae and allied families J. Jpn. Bot. 12 57 161

  • Sen, S. 1973 Structural hybridity intra- and interspecific levels in Lilliales Folia Biol. (Cracow) 21 183 197

  • Sharma, A.K. & Chaudhuri, M. 1964 Cytological studies as an aid in assessing the status of Sanseviera, Ophiopogon, and Curculigo Nucleus 7 43 58

  • Sheriff, A. & Singh, B.K.S. 1975 Hexaploid wild populations of Ophiopogon intermedium from Shiradi Ghats, Karnataka State. Proc. Indian Sci. Congr. Assoc. 62:117

  • Skinner, H.T. 1971 Some liriopogon comments J. Royal Hort. Soc. 96 345 350

  • Tamura, M.N. 1990 Studies on the genus Ophiopogon (Liliaceae) of Phu Kradung in Thailand Acta Phytotax. Geobot. 41 1 6

  • Tanaka, N. 2000 Taxonomic notes on Ophiopogon of South Asia VII J. Jpn. Bot. 75 191 212

  • Tanaka, N. 2001a Taxonomic notes on Ophiopogon (Convallariaceae) of East Asia (I) J. J. Bot. 76 59 76

  • Tanaka, N. 2001b Taxonomic notes on Ophiopogon (Convallariaceae) of East Asia (II) J. Jpn. Bot. 76 151 165

  • Tanaka, N. 2001c Taxonomic notes on Ophiopogon (Convallariaceae) of East Asia (III) J. Jpn. Bot. 76 205 218

  • Terasaka, O. & Tanaka, R. 1974 Cytological studies on the nuclear differentiation in microspore division of some angiosperms Bot. Mag. Tokyo 87 209 217

    • Search Google Scholar
    • Export Citation
  • Thunberg, C.P. 1780 Convallaria japonica November Act. Reg. Soc. Upsala 3 208

  • Trueblood, C.E. 2009 An estimate of the commercial value of potentially invasive nursery crops grown in North Carolina, p. 63–75. In: An Invasive Species Assessment System for the North Carolina Horticultural Industry. MS thesis, North Carolina State University, Raleigh, NC

  • Wang, G., Meng, Y. & Yang, Y. 2013 Karyological analyses of 33 species of the tribe Ophiopogoneae (Liliaceae) from Southwest China J. Plant Res. 126 597 604

    • Search Google Scholar
    • Export Citation
  • Wang, K.W., Ju, X.Y., Zhang, L., Wang, W. & Shen, L.Q. 2012 A novel C27-steroidal glycoside sulfate from Liriope graminifolia Yao Xue Xue Bao 47 619 623

  • Wang, S.-F. & Xu, J.-M. 1990 Report on karyotypes of Smilacina tatsienensis and Ophiopogon japonicus Acta Phytotaxonomica Sinica 28 207 210

  • Westfall, J.J. 1950 Aneuploidy in Liriope muscari Bailey Amer. J. Bot. 37 667

  • Wu, T., Wang, Y. & Yu, B. 1998 Classification of four species of plant genus Liriope (Liriope Lour.) using RAPD Chin. Tradit. Herbal Drugs 29 37 40

  • Yamashita, J. & Tamura, M.N. 2001 Karyotype analysis of six species of the genus Ophiopogon (Convallariaceae-Ophiopogoneae) J. Jpn. Bot. 76 100 119

    • Search Google Scholar
    • Export Citation
  • Yang, Y.-P., Li, H., Liu, X.-Z. & Kondo, K. 1990 Karyotype study on the genus Ophiopogon in Yunnan Acta Bot. Yunnan. Suppl. 3 94 102 [in Chinese with English abstract]

    • Search Google Scholar
    • Export Citation
  • Yu, B.-Y., Qiu, S.-X., Zaw, K., Xu, G.-J., Hirai, Y., Shoji, J., Fong, H.S. & Douglas, A. 1996 Steroidal glycosides from the subterranean parts of Liriope spicata var. prolifera Phytochem. 43 201 206

    • Search Google Scholar
    • Export Citation
  • Zhang, D.M. 1998 Systematics of tribe Ophiopogoneae (Liliaceae s.l.) with special reference to karyotypes and chromosomal evolution Cathaya 10 1 154

    • Search Google Scholar
    • Export Citation
  • Zhou, Q., Zhou, J., Chen, J. & Wang, X. 2009 Karyotype analysis of medicinal plant Liriope spicata var. prolific Biologia 64 680 683

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