4.'!l' Ulmace.e. 



ELM FAMILY. ULMACE/E. 



Trees and shiiibs with tou^li wood and of about one hundred and forty species grouped 



in thirteen genera and widelj' distributed tliroughout the temperate regions of the northern 



hemisphere. Fire genera are represented in the United States, and three of these bj' trees 



■of tile eastern and soutliern states. They are characterized as follows : 



Leaves deciduous, simple, jietolate, alternate, in two ranks, serrate, pinnately veined, 

 unecjual at base, conduplicate in the bud and with usually fugacious stipules; buds with 

 several scales. Fhjucrs small, perfect, moncecious or polygamous, clustered, or the pistillate 

 solitary : calyx regular, 4-'J-parted or lobed ; petals none ; stamens as many as the lobes of the 

 calyx and opposite them, with straight exserted filiments and introrse 2-celled anthers opening 

 longitudinally ; ovary 1-celled with solitary, anatropous or amphitropous ovule suspended 

 fiom apex of the cell ; styles two. Fruit a samera. drupe or nut ; seed with little or no 

 albumen, straight or curved embryo, and usually fiat cotyledons. 



KlOY TO THE GKXEKA. 



a Fruit a samara: flowers perfect and usually expanding before the leaves.... Ulmus. 



a- Fruit papillose nut-like: flowers polygamous, expanding with the leaves Planera. 



a' Fruit a drupe ; flowers on the new growth of the season Celtis. 



THE ELMS. Genus ULMUS L. 



Trees or rarely shrubs with scaly ridged bark,' heavy tough wood and somewhat zigzag 

 branehlets, and of about eighteen species, of which six or seven are found in eastern United 

 States and four of these in the northeastern states. None are found in the Pacific states. 



Ijcarcs inequilateral, straight-veined and simply or doubly serrate: stipules scarious 

 caducous: buds with several closely imbricated scales in 2 ranks. Flowern from axillai-y 

 buds on twigs of the previous season's growth and usually expanding before the leaves (or in 

 autumn from the axils of the leaves of the season), mostly perfect and in fascicles or 

 racemes, Avith bibraeteolate pedicels ; calyx campanulate, membranaceous persistent with 

 4-0 imbricated lobes; stamens .5-G, exserted with slender filaments and oblong anthers; ovary 

 sessile or stalked, compressed with 2 divergent styles stigniatic on inner faces, 1-celled and 

 containing a single amphitropous ovule. Fruit a flat orbicular or oblong membranaceous 

 1-seeded samara winged all around (or excepting apex I. subtended by the Avithered calyx 

 and sometimes tipped with the remnants of the styles; seed compressed with straight embryo 

 and no albumen, 



Llmiis is the ancient Latin name of the Ehn. 



KEY TO THE SPECIES. 



a Leaves smooth or nearly so above and samara with wing-like ciliate margin 

 b As broad as seed portion 



Samara with glabrous sides; buds glabrous and bluntly pointed.. U. Americana. 



Samara hairy on sides : buds acuminate and puberulous U. racemosa. 



b' Narrower than seed portion ; branehlets corky winged ; samara narrow, stipitate and 



hirsute XT. alata. 



a,- Leaves very rough above: samara not ciliate; buds rusty-tomentose. ... U. pubescens. 



For sprcicx sec pp. 1S2-1S9. 



THE PLANER TREE. Genus PLANERA Gmelin. 



A genus of a single species of small trees of southeastern United States and the lower 



Mississippi valley, resembling the p]lms. The characters are given in the description of species. 



It is named after Joliii Jucob Planer, a (ierman I'refessor of Botany of the eighteenth 



century. 



For species sec pp. 100-19 1. 



THE HACKBERRIES. Genus CELTIS L. 



Trees and shrubs of fifty or sixty species, widely distributed throughout the teiuperate 



and tropical regions. Four species are found in North America, two being shrubs of the 



southern states and southward and the other two trees entitled to consideration here. 



Learcs pointed, inequilateral jjinnately-veined or sometimes .S-n-veined at ba.se: stipules 

 membranous, caducous. Flowers polygamo-moncecious, small, appearing with the unfolding 

 of the leaves or soon after on the branehlets of the year, pedicellate : the staminate in 

 fascicles near the base of the shoot and the pistillate solitary or few together from the axils 



