ULMACEAE 363 



Leaves alternate, often 2-ranked : blades simple, usually inequilateral, oblique 

 at the base, commonly scabrous : stipules fugacious. Flowers inconspicuous, 

 perfect, polygamous, or monoecious, in axillary or lateral cymes, racemes or 

 clusters. Perianth a green or slightly colored calyx. Sepals 4-5 or rafely 3-8, 

 more or less united at the base, imbricated. Androecium usually of as many 

 stamens as there are sepals. Filaments inserted at the base of the perianth 

 opposite the lobes, distinct. Anthers opening lengthwise. Gynoecium of 2 

 united carpels. Ovary 1-2-celled, free. Stigmas 2. Ovule solitary, pendulous, 

 anatropous or amphitropous. Fruit a stalked samara or a drupe, or nut-like. 

 Seed with a membranous testa. Endosperm wanting or scant. Embryo with 

 flat or conduplicate cotyledons. 



Fruit dry, a samara, or nut-like : embryo straight. 



Flowers mostly perfect : fruit a samara winged all around. 1. ULMUS. 



Flowers polygamo-monoecious : fruit nut-like, bearing wart-like tubercles. 2. PLANERA. 



Fruit a drupe : embryo with conduplicate cotyledons. 



Flowers solitary or merely clustered in the axils : drupe solitary. 3. CELTIS. 



Flowers in dichotomous cymes : drupes cymosely disposed. 



Stigmas 2-cleft : sepals of staminate flowers imbricated : plants armed. 4. MOMISIA. 



Stigmas entire : sepals of staminate flowers valvate : plants unarmed. 5. TREMA. 



1. ULMUS L. 



Shrubs or trees, with a furrowed bark and flexuous branchlets which are sometimes 

 furnished with corky wings. Leaves 2-ranked : blades oblique, straight-nerved, rigid, 

 serrate, deciduous. Flowers perfect (American species), in axillary clusters or cymes, 

 articulated to the pedicels which are furnished with 2 scales. Calyx campanulate, mem- 

 branous, 4-9-lobed, usually 5-lobed. Stamens exserted : filaments filiform or slightly 

 flattened : anthers extrorse, erect, einarginate at the apex, subcordate at the base. Ovary 

 sessile or short-stalked, flattened, 1-celled or rarely 2-celled, surmounted by 2, often re- 

 curved, introrse stigmas. Samara suborbicular or oblong, its membranous wing subtended 

 by the persistent calyx. Seed flattened. ELM. 



Flowers and fruit autumnal, in the axils of the leaves. 



Leaf-blades obtuse : fruit short-ciliate. 1. U. crassifolia. 



Leaf-blades acute or acuminate : fruit long-ciliate. 2. U. serotina. 

 Flowers and fruit vernal, on the naked branches. 



Leaf-blades smooth or roughened above : flowering pedicel longer than the calyx. 



Branches with corky wings. 3. U. alata. 

 Branches without corky wings. 



Leafy twigs purple, glabrous : samara ovate, the tips erect or nearly so. 4. U. Floridana. 



Leafy twigs pubescent : samara oval or obovate, the tips converging. 5. U. Americana. 



Leaf-blades very scabrous-pubescent : flowering pedicel shorter than the calyx. 6. 17. fulva. 



1. Ulmus crassifolia Nutt. A tree, reaching a maximum height of 30 m. and a 

 trunk diameter of 1 m., its twigs and lower leaf surfaces pubescent. Leaf -blades firm and 

 leathery, inequilateral, usually oblong, elliptic or ovate, obtuse, finely and often doubly 

 serrate, mostly rounded at the oblique base, very rough above, more or less pubescent 

 beneath, short-petioled : flowers autumnal, in axillary clusters : pedicels very short : calyx 

 campanulate-turbinate, the lobes oblong or linear-oblong : samara oval, undulate, 8-10 

 mm. Jong, finely pubescent, produced into 2 short beaks : seed ovate. 



On prairies and along rivers, Arkansas to Mississippi and Texas, and in northern Mexico. 

 Flowers in the late summer and fall ; matures its fruit in September and October. 



2. UlmuB serotina Sarg. A tree, reaching a height of 16 m., with a maximum 

 trunk diameter of nearly 1 m., the branches spreading or pendulous, often with 2-3 corky 

 wings, the buds acute, about 6 mm. long. Leaf-blades oblong to oval or broadest above the 

 middle, 5-8 cm. long, firm, often relatively thin, lustrous and yellow-green above, coarsely 

 toothed, with a prominent midnerve and about 20 pairs of lateral nerves ; petioles mostly 

 about 6 mm. long : racemes 2-4 cm. long, many-flowered : pedicels 2-4 mm. long : calyx 

 reddish brown, 2-3 mm. long : anthers yellow : samara oblong-elliptic, 10-12 mm. long, 

 ciliate with silvery hairs. 



On banks and bluffs, Tennessee, Georgia and Alabama. Fall ; fruit ripen in November. 



3. Ulmus alata Michx. A tree, reaching a height of 20 mm., with a trunk diameter 

 of 1 m., the branches corky-winged. Leaf-blades firm, usually narrowly-elliptic or elliptic- 

 oblong, rarely nearly oval or ovate-lanceolate, 2-10 cm. long, acute or short-acuminate, 

 doubly or triply serrate, equilateral or slightly inequilateral, obtuse or slightly cordate at 

 the base, short-petioled : flowers in clustered racemes, vernal : pedicels 4-8 mm. long : 

 calyx campanulate, the lobes ovate or suborbicular : samara elliptic, 5-6 mm. long, conspicu- 



