2. Aesculus Linnaeus, Sp. Pl. 1: 344. 1753.
七叶树属 qi ye shu shu
Authors: Nianhe Xia & Nicholas J. Turland
Actinotinus Oliver, p.p.; Hippocastanum Miller; Pavia Miller.
Trees or shrubs, deciduous. Winter buds large, viscid resinous or not, with several pairs of imbricate scales; scales abaxially glabrous or sparsely puberulent. Leaf blade 5-11-foliolate; leaflet blades without scattered, conspicuous glands, margin crenate to serrate or compoundly so. Thyrse cylindric or conic; branches simple; bracts absent. Flowers often large and showy. Sepals connate to form a tubular to campanulate calyx tube. Petals often unequal, base clawed, limb obovate, oblong, oblanceolate, or spatulate. Ovary without a gynophore; style long, slender; stigma depressed globose, entire or obscurely lobed. Capsule depressed globose to pyriform, without a long gynophore, often 1-seeded; pericarp usually smooth, often dotted, rarely verrucose or prickly. Seeds depressed globose to pyriform, large (2-7 cm); testa brown; hilum large, pale, occupying 1/3-1/2 of seed. x = 20.
Twelve species: mainly in North America (United States, Baja California in Mexico) and Asia from the Himalayas to Japan (Afghanistan, Bangladesh, Bhutan, China, India, Japan, Kashmir, Laos, Myanmar, Nepal, Pakistan, Thailand, Vietnam), one species in SE Europe (Albania, Bulgaria, Greece, former Yugoslavia); four species (one endemic, two introduced) in China.
Fang (Acta Sci. Nat. Univ. Szechuan. 1960(3): 77-125. 1962) published a revision of the Hippocastanaceae in China, including 12 new species, for which six of the names were not validly published, either because no Latin description was provided, no type was indicated, or more than one type was indicated. Fang later (in FRPS) identified three of these entities as species of Araliaceae: "Aesculus chingsiensis" as Acanthopanax evodiifolius Franchet, "Aesculus chinpingensis" as Brassaiopsis glomerulata (Blume) Regel, and "Aesculus kwangsiensis" as Schefflera octophylla (Loureiro) Harms.
The W Himalayan Aesculus indica (Wallich ex Cambessèdes) Hooker (Bot. Mag. 85: t. 5117. 1859; Pavia indica Wallich ex Cambessèdes in Jacquemont, Voy. Inde 4(Bot.): 31. 1841) is distributed from NE Afghanistan, through N Pakistan, Kashmir, and N India, to C Nepal, and might yet be found in adjacent parts of Xizang in China.
The leaves, flowers, and large seeds contain the poisonous compound aesculin.