352 The Hackberries 



brown, later becoming gray. The leaves vary from ovate to oblong-lanceolate and 

 from 2 to 6 cm. long; they are either blmit or pointed, toothed, except at the 

 rounded or somewhat heart-shaped base, thick, sHghtly hairy when young, glabrous, 

 and a Uttle rough on both sides when mature, dark green above, paler beneath; 

 the leaf-stalks are 7 mm. long or less, and the red stipules fall while the leaves 

 are imfolding. The staminate flowers are nearly stalkless in clusters on twigs of 

 the preceding year, the pistillate and perfect ones borne 2 or 3 together in the 

 axils of young leaves of the season, and stalked; both kinds are very small. The 

 bell-shaped calyx is rather deeply 4-lobed or 5-lobed, the lobes blunt; there is no 

 corolla; in the staminate and perfect flowers there are as many stamens as there 

 are calyx-lobes, with long filaments and short ovate anthers; the ovary has a short 

 stipe, is i-celled, tubercled, and bears 2 styles, which are stigmatic on the upper 

 side. The fruit is a curious structure, oblong-ovoid, nut-like, covered with soft 

 processes, which grow out from the tubercles on the ovary; it is about 6 mm. long, 

 and about as long as its stalk, the calyx persistent at the base. 



The wood is soft and light brown with a specific gravity of only 0.53. It is 

 of no economic value. 



III. THE HACKBERRIES 



GENUS CELTIS [TOURNEFORT] LINNAEUS 



iJELTIS is composed of about 60 species of trees and shrubs, widely 

 distributed in temperate and tropical regions of both the Old World 

 and the New. Besides the kinds here described, which are closely 

 interrelated, several occur in the West Indies and Central America; 

 Celtis jamaicensis Planchon is endemic in Jamaica; Cdtis caudata Planchon and 

 others in Mexico, and C. trinervia Lamarck in Cuba, Jamaica, and Santo Do- 

 mingo; the European and Asiatic Cdtis australis Linnaeus is the type of the genus. 

 The genus Momisia, which includes several American species, two of which occur 

 as shrubs in the southern States, is here regarded as distinct from Celtis, and C. 

 monoica Hemsley, from Huasteca, Mexico, which has equilateral, regularly pin- 

 nately veined leaves, must also be excluded from Celtis when its fruit becomes 

 known. 



The name Celtis was used by Pliny for an African lotus-tree, but was taken up 

 by Linnseus, following Toumefort, for the trees with which it is associated in 

 modem times. 



The bark of the Hackberries often developes numerous corky warts or ridges, 

 which are sometimes very conspicuous on old trees. The branching is irregularly 

 pinnate, at least in all the North American species, and the twigs are not armed 

 with thorns as they are in Momisia. The wood is tough and the sap watery. 

 The leaves are unequal-sided, often prominently so, and mostly unfold with the 

 flowers or a little before them in the spring; they are stalked, and provided with 



