MORACEAE (MULBERRV FAMILY) 143 



spinulose: cup hemispheric, 7-10 mm. broad; scales ovate, strongly corky- 

 thickened on the back; acorn barrel-shaped or cylindric, 10-15 mm. long, 

 6-7 mm. in diameter, brown (Q. pungens Liebm., Rydb. 1. c). — Colorado to 

 Texas and Arizona. 



31. ULMACEAE Mirbel. Elm Family 



Trees or shrubs with alternate serrate pinnately veined leaves, with fugaci- 

 ous stipules. Flowers small, monoecious, dioecious, or polygamous, clustered 

 or the pistillate solitary. Perianth of 4-9 distinct sepals. Stamens as many 

 as the sepals. Ovary 1-celled, superior. Fruit a samara, drupe, or nut. 



AH the flowers cl\istered; fruit a samara . 1. Ulmus. 



Pistillate flowers solitary; fruit a drupe .2. Celtig. 



1. ULMUS L. Elm 



Trees with polygamous purplish or yellowish flowers in lateral clusters, ap- 

 pearing before the shbrt-petioled oblique or unequally somewhat heart-shaped 

 leaves. Perianth campanulate. Stamens slender, 4-9. Styles 2, divergmg, 

 stigmatic along the inner marginj Fruit l^seeded, winged all around. 



1. Ulmus americana L. Sp. PL 226. l'^53. Large and well-known orna- 

 mental tree, usually with spreading branches and drooping branchlets: buds 

 and branchlets glabrous: branches not corky: leaves ob ovate-oblong or oval, 

 abruptly pointed, sharply and often doubly serrate <5-10 cm. long), soft- 

 pubescent beneath, or soon glabrous: flowers in close fascicles: calyx with 7-9 

 roundish lobes: fruit glabrous except the margins (12 mm. long), its sharp 

 points incurved and closing the notch. — Probably not indigenous in our range, 

 but largely grown as a shade tree. 



2. CELTIS L. Hackberrt 



Leaves pointed, petioled. Flowers greenish, axillary, the fertile solitary or in 

 pairs, peduncled, appearing with the leaves; the lower usually staminate only, 

 m little fascicles or racemose along the base of the branches of the, season. 

 Calyx 5-6-parted. Stamens 5-6. Ovary 1-celled. Fruit globjilar. 



1. Celtis occidentalis L. Sp. PL 1044. 1753. Leaves reticulated, ovate, 

 cordate-ovate and ovate-lanceolate, taper-pOinted, sharply serrate, some- 

 times sparingly so or only towards the apex, scabrous but mostly glabrous 

 above^ usually soft-pubescent beneath, at least when young: fruit reddish or 

 yellowish, becoming dark purple. — ^From Colorado to Wisconsin and east- 

 ward. A small or Iniddle-sized tree with the aspect of an elm. 



32. , MORACEAE Lindl. Mulberry Family 



Trees, shrubs, or herbs with opposite lobed leaves (our only native genus an 

 herbaceous vine). Flowers dioecious. Calyx 5-parted. Petals none. Sta- 

 mens 5. Ovary superior, 1-celled, 1-ovuled, becoming a glandular or resinifer- 

 ous achene. — Ulmaceae in part. 



1. HUMULUS L. Hop 



Twining rough perennials, with stems almost prickly downwards, and mostly 

 opposite, heart-shaped, and palmately 3-7-lobed leaves. Sterile flowers with 

 6 sepals and 5 erect stamens. Ferjiile flowers in short spikes with leafy im- 



