The genus Carya comprises 20 taxa globally, with 14 species found in North America ( Wood and Grauke, 2011 ). Divided into three subgenera, the “true hickories” (sect. Carya) and “pecan hickories” (sect. Apocarya) comprise the 14 species found
Hickories are deciduous woody perennials of the genus Carya ( Elias, 1980 ). Most are stately trees of medium to large size, exhibiting grand ornamental features that justify their use as shade trees. All are recognized for their large
`Oconee' pecan [Carya illinoinensis (Wangenh.) K. Koch] scions were grafted on seedling rootstock from nine open-pollinated seedstocks. Rootstock included three seedstocks each of pecan, water hickory [C. aquatica (F. Michx.) Nutt.], and their interspecific hybrid, Carya × lecontei (Little). Pecan seedlings had the largest basal diameters and water hickory seedlings the smallest. Seedlings of `Elliott' and `Curtis' seedstocks were larger than seedlings from `Moore' seedstock. Pecan and C. × lecontei seedlings were grafted more successfully than water hickory. Graft success varied among seedstocks of pecan and C. × lecontei Foliage color of seedlings, possibly indicative of iron nutritional status, was influenced by species; pecan seedling leaves were darker green than those of water hickory seedlings, but similar to C. × lecontei leaves. `Oconee' scion leaves were darker green on pecan rootstock than when grafted on C. × lecontei rootstock.
`Oconee' pecan (Carya illinoinensis (Wangenh.) K. Koch) was grafted on seedling rootstocks from nine open-pollinated seedstocks. Rootstocks included three seedstocks each of pecan, water hickory (C. aquatica (F. Michaux.) Nutt.) and their hybrid, Carya X lecontei (Little). Pecan seedlings had the largest basal diameter, water hickory seedlings the smallest, and hybrid seedlings were intermediate. Seedlings of `Elliott' and 'Curtis' seedstocks were larger than seedlings from `Moore' seedstock. Pecan and hybrid seedlings were more successfully grafted than water hickory. Graft success varied between seedstocks of the hybrid, with some as high as pecan. Foliage color of seedlings, indicative of iron nutrient status, was influenced by the species of rootstock: pecan seedlings were darker green than water hickory seedlings, but were inseparable from hybrid seedlings. `Oconee' scions on pecan seedlings were darker green than when grown on hybrid seedlings.
enclosed in a dehiscent husk that splits along more or less winged sutures to release the hard-shelled nuts. Nuts are tan to brown, mottled with black stripes at the apex and spots at the base. Shells are relatively thin as compared with most hickories, and
In vivo pollen tube growth of pecan [Carya illinoinensis (Wangenh.) K. Koch] was estimated to be ≈ 150 μm·hour-1 from 3 to 8 hours postpollination. Pollen tubes averaged 47, 194, 405, and 946 μm after 2, 3, 4, and 8 hours postpollination, respectively. Pollen tube growth was strongly influenced by temperature, and in vitro studies demonstrated pollen germination and tube growth were optimal at 27C for `Cape Fear' pecan. In in vivo studies, tubes of cross-pollen did not grow significantly faster than tubes of self-pollen. Pollen tubes of water hickory [C. aquatica (Michx. f.) Nutt.] grew significantly faster than those of C. illinoinensis. Bitternut [C. cordiformis (Wangenh.) K. Koch] and mockernut hickory (C. tomentosa Nutt.) pollen tubes grew significantly slower on pecan stigmas than did pecan pollen. Pollen arriving first on the stigma has a decided advantage for fertilization success of pecan. The fertilization success rate of pecan pollen arriving 24 hours after first pollen arrival was <3%.
1 Research Horticulturist and Curator, National Clonal Germplasm Repository for Pecans and Hickories. 2 Professor. 3 Professor. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations
Florida Agr. Expt. Sta. J. Series no. R-01597. The assistance of David Brown and support by Kimberly-Clark, Roswell, Ga., and Reemay, Old Hickory, Term., are appreciated. The cost of publishing this paper was defrayed in part by the payment
Educational and research opportunities utilizing native plant species are being developed by the LSU Agricultural Center through the recent establishment of a native plant arboretum at the Calhoun Research Station. Plants indigenous to Louisiana and surrounding states are being collected and planted in the arboretum for evaluation of potential values for landscaping, in food industries, and/or wildlife management. Native trees being studied include species of oak (Quercus), maple (Acer), hickory (Carya), and dogwood (Cornus). Lesser known species of holly (Ilex) and hawthorn (Crataegus), are being evaluated for commercial production and landscape potential. Fruit being collected for field orchard studies include mayhaw (Crataegus opaca), pawpaw (Asimina triloba), and several native plums (Prunus spp.).
A control burn was conducted in a mixed black oak—white oak—post oak stand to determine the effectiveness of fire at removing midstory and understory trees. The midstory and understory was predominately invading species of red maple, dogwood, black cherry, black gum, and mockernut hickory with lesser amounts of canopy species—black oak, white oak, post oak, and blackjack oak. A total of 17,000 stems/ha were top killed. All stems below 10 cm (15,600 stems/ha) were killed and all of the invading species were all top killed. Large black oak (greater than 20 cm) were killed by hypoxylon which may or may not have been related to fire. Soil pH increased from 4.6 (before) to 5.7 after the burn. The litter layer was almost completely removed. The biomass of the litter layer the year after the burn was 23% of the biomass before burning. Herbaceous plants began to invade the site in the first summer.