Garden, 2006 ), and the U.S. Department of Agriculture (USDA) National Plant Germplasm System ( USDA, 2006 ). Taxonomy of Taxodium Baldcypress, pondcypress, and montezuma cypress are three taxa recognized historically in the genus Taxodium . Baldcypress
Geoffrey C. Denny and Michael A. Arnold
Andrew R. King, Michael A. Arnold, Douglas F. Welsh, and W. Todd Watson
Baldcypress, Taxodium distichum (L.) Rich., is a highly adaptable tree of significant ecological importance in the southeastern United States ( Arnold, 2008 ; Pezeshki and DeLaune, 1994 ). Baldcypress is typically propagated commercially from
Lijing Zhou, David L. Creech, Ken W. Krauss, Yin Yunlong, and David L. Kulhavy
three separate species of Taxodium : Taxodium distichum (baldcypress), T. ascendens (pondcypress), and T. mucronatum (Montezuma cypress). Although the taxonomic relationships among these three species, or varieties, of Taxodium remain a source
Garry Vernon McDonald, Geoffrey C. Denny, Michael A. Arnold, Donita L. Bryan, and Larry Barnes
Baldcypress ( Taxodium distichum ) is a medium to large deciduous tree with demonstrated adaptability to many difficult landscape sites, including urban locations with compacted or depleted soils, and exposure to poor air and water quality
Geoffrey C. Denny, Michael A. Arnold, and Wayne A. Mackay
nice form ( Arnold, 2002 ; Cox and Leslie, 1988 ). Two varieties, T. distichum var. distichum (baldcypress) and T. distichum var. imbricarium (Nutt.) Croom (pondcypress), have good fall color in some areas, whereas T. distichum var. mexicana
Geoffrey Denny, Michael A. Arnold, and Donita Bryan
Seedlings from 15 open-pollinated families of Taxodium distichum (L.) Rich. native to the Gulf Coast, central and south Texas, and Mexico, were evaluated for growth and foliar chlorosis development on field sites in Texas with acidic to alkaline soils. Forty seedlings per family were rated for level of chlorosis, height, and trunk diameter after two growing seasons in the field. Families grown on acidic soils did not differ in chlorosis ratings. Families from Mexico and south Texas had the lowest levels of chlorosis in the field, followed by those from central Texas, and then those from the Gulf Coast. Additionally, eight of the families were subjected to a greenhouse screening experiment with four levels of KHCO3 (0, 4, 8, 12 mM). These were evaluated for height, trunk diameter, shoot and root dry mass, and level of chlorosis and leaf necrosis. Family differences were less apparent during greenhouse screening experiments than in the field. Mexican families were significantly less chlorotic than other families at higher levels of alkalinity in the greenhouse. There was also a trend for height and shoot dry masses of western populations to be less adversely affect by higher alkalinity levels than more eastern populations.
Michael A. Arnold, Don C. Wilkerson, Bruce J. Lesikar, and Douglas F. Welsh
Studies were conducted using Zea mays L. and Taxodium distichum L. seedlings as model systems to study Cu leaching from Cu(OH)2-treated containers. Initial experiments developed Cu toxicity curves (as CuSO4) in an inorganic (sand) or organic (bark-sand) medium with single (acute) or multiple (chronic) applications. A second pair of experiments investigated short-term (35 days) Cu accumulation and plant responses to irrigation with water (125 mL/plant per day) recycled through a fixed reservoir volume (9.5 L) from 0.7-L Cu(OH)2-treated containers filled with an inorganic or organic medium. Finally, plant responses and Cu leaching were monitored during growth in 2.3-L Cu(OH)2-treated containers filled with two organic media fertigated with high (8.0) or low (6.5) pH solutions. Different Cu(OH)2 concentrations and application methods were tested. Leachate data from the latter studies were used to calculate potential Cu concentrations in nursery runoff using various water application methods and pot spacings. Expression of Cu toxicity symptoms depended on exposure, concentration, and medium for each species. Plants subjected to chronic exposure and grown in an inorganic medium developed toxicity symptoms at lower doses than plants subjected to acute exposure and grown in an organic medium. Several measures of plant growth were greater for both species when grown in 0.7-L Cu(OH)2-treated containers, but not in 2.3-L containers. Plants in Cu(OH)2-treated containers seldom exhibited Cu toxicity symptoms in shoot tissues, even with an inorganic medium. Soluble Cu content of the recycled solution from Spin Out-treated containers increased slightly (<1.2 mg·L-1) during the 35-day experiment. Longer-term studies with nonrecycled leachate from 2.3-L containers indicated that Cu leaching increased after 60 to 90 days. Copper leaching was greater with the combination of applied solution of pH 6.5 and bark-sand-peat medium than with the combination of applied solution of pH 8.0 and bark-sand medium, and increased with greater concentrations of Cu(OH)2 in container wall treatments or when containers were filled before latex carrier was dried. Calculations of potential nursery runoff indicated that the levels of soluble Cu in effluent for most concentrations and spacings projected were below EPA action levels for potable water (1.3 mg·L-1) when overhead irrigation was used.
Larry J. Shoemake and Michael A. Arnold
Zea mays L. and Taxodium distichum L. seedlings were grown for 35 days in sand or 3:1 milled pine bark:sand media in 0.7 liter containers. Containers were painted on interior surfaces with 100 g Cu(OH)2/liter or 200 g Cu(OH)2/liter latex carrier (Spin Out™) or not. Five seedlings of each treatment combination were watered daily from 9.5 liter reservoirs with 100 ml of recycled fertilizer (20N-8.7P -16.6K. pH 6.0) solution initially containing 0.036 mg Cu/liter. Fertilizer solutions containing 0.036, 5, 10, 100, or 1000 mg Cu/liter were used to develop toxicity response curves with additional seedlings. Growth of both species in both media was increased by Spin Out treatments. Soluble Cu content of the recycled solution from Spin Out treated containers increased slightly (<1.2 mg/liter) during the experiment. Soluble Cu in leachate from Cu-treated containers ranged from 0.2 to 5 mg/liter with sand and from 0.30 to 1.2 mg/liter with bark. Soluble Cu in leachatc from non-treated containers ranged from 0.02 to 0.40 mg/liter with sand and 0.10 to 0.86 mg/liter for bark media.
Andrew R. King, Michael A. Arnold, Douglas F. Welsh, and W. Todd Watson
Baldcypress, Taxodium distichum (L.) Rich., is a species of ecological significance in the southeastern United States ( Arnold, 2008 ; Pezeshki and DeLaune, 1994 ). It is highly valued for its ornamental characteristics and site adaptability
Michael A. Arnold and Daniel K. Struve
Seedlings of nine coarse-rooted species–sawtooth oak (Quercus acutissima Carruth), white oak (Q. alba L.), cherrybark oak (Q. falcata var. pagodifolia Elliott), post oak (Q. stellata Wangenh.), black walnut (Juglans nigra L.), pignut hickory [Carya glabra (Mill.) Sweet], pecan [C. illinoinensis (Wangenh.) C. Koch], Chinese chestnut (Castanea mollissima Blume), and common baldcypress [Taxodium distichum (L.) L. Rich]—were grown for one growing season in nontreated containers or in containers treated on their interior surfaces with white interior latex paint containing 100 g Cu(OH)2/liter. Seedlings of each species and container treatment were harvested twice: once after being transplanted from 3.2- to 15.0-liter containers and at the end of the growing season. Cupric hydroxide-treated containers decreased the amount of circled, kinked, and matted roots formed at the container wall-medium interface in all species tested. Plants grown in Cu(OH)2-treated containers also had altered root dry-weight partitioning. The partitioning patterns were species specific and included 6% to 20% increases in the percentage of root dry weight in interior vs. exterior portions of the rootball (white oak, black walnut, Chinese chestnut, and baldcypress), 10% to 21% increases in the percentage of root dry weight in upper vs. lower halves of the rootball (sawtooth oak, cherrybark oak, black walnut, and baldcypress), and an increase in the percentage of primary lateral roots (lateral roots originating from taproots or roots functioning as taproots) on the upper (proximal) half of taproots (cherrybark oak, pecan, and baldcypress). Nutrients in leaves, stems, and roots of sawtooth oak seedlings were analyzed at both harvests. Seedlings grown in Cu(OH)2-treated containers had more Cu in most plant tissues than nontreated seedlings. Also, seedlings grown in Cu(OH)2-treated containers had higher total Ca and Mg concentrations at transplanting and higher total N and Zn concentrations at the end of the growing season than nontreated seedlings.