2. Castanea Miller, Gard. Dict. Abr., ed. 4. 1754.
Chestnut, châtaignier [Classical Latin, from Greek kastanaion karuon, nut from Castania, probably referring either to Kastanaia in Pontus or Castana in Thessaly]
Trees or shrubs , winter-deciduous, sometimes rhizomatous. Terminal buds absent, pseudoterminal bud (axillary bud of youngest leaf) ovoid, with 2 unequal opposite outer scales enclosing several imbricate inner scales. Leaves: stipules prominent on new growth, soon deciduous. Leaf blade thin, somewhat leathery, secondary veins unbranched, ±parallel, extending to margin, each vein ending in sharp tooth or well-developed awn. Inflorescences staminate or androgynous, axillary, spicate, erect, rigid or flexible; androgynous inflorescences with pistillate cupules/flowers toward base and staminate flowers distally. Staminate flowers: sepals distinct; stamens 12(-18), typically surrounding indurate pistillode covered with silky hairs. Pistillate flowers 1-3 per cupule; sepals distinct; carpels and styles typically 6(-9). Fruits: maturation in 1st year following pollination (termed annual by many authors); cupule 2-4-valved, valves connate marginally until maturity, ±completely enclosing nut(s), spiny, spines irregularly branched, often interlocking, densely or sparsely covered in simple hairs; nuts 1-3 per cupule, plano-convex, or if 3, then central nut often reduced and flattened, or if solitary, then often rounded in cross section, not winged, adjacent nuts not separated by internal cupule valves. x = 12.
Species ca. 8-10 (3 in the flora, often interpreted as 2): North America, Europe, Asia.
As evidenced by United States breeding programs, all species are probably interfertile (including American × Asian species). Local morphologic intergradation between species is to be expected.
SELECTED REFERENCES
Hardin, J. W. and G. P. Johnson. 1985. Atlas of foliar surface features in woody plants, VIII. Fagus and Castanea (Fagaceae) of eastern North America. Bull. Torrey Bot. Club 112: 11-20. Johnson, G. P. 1988. Revision of Castanea sect. Balanocastanon (Fagaceae). J. Arnold Arbor. 69: 25-49. Paillet, F. L. 1993. Growth form and life histories of American chestnut and Allegheny and Ozark chinquapin at various North American sites. Bull. Torrey Bot. Club 120: 257-268. Paillet, F. L. and P. A. Rutter. 1989. Replacement of native oak and hickory tree species by the introduced American chestnut Castanea dentata in southwestern Wisconsin, USA. Canad. J. Bot. 67: 3457-3469. Tucker, G. E. 1975. Castanea pumila var. ozarkensis (Ashe) Tucker, comb. nov. Proc. Arkansas Acad. Sci. 29: 67-69.
