APETALOUS EXOGENOUS PLANTS. 497 



styles short', fruit nut-like, coriaceous, wingless; emhrijo 

 straight, without albumen. — Small trees, with the foliage 

 of the Elm. 



P. AQUATICA, Gmel. Leaves ovate, short-petioled, acute, 

 serrate, roughish; flowers in small, roundish clusters, ap- 

 pearing before the leaves ; mit ovate, covered with warty 

 scales. Kiver-swamps. February and March. — A tree, 

 20°-30° high ; leaves I'-l^' long. 



CELTIS, Tourn. ISTettle-tkee. 



Flowers perfect or polygamous, apetalous ; calyx of five 

 sepals ; stamens 5 ; anthers introrse ; ovary 1-celled ; styles 

 2, slender, pubescent; drupe globose; embryo curved 

 around scanty gelatinous albumen ; cotyledons wrinkled. — 

 Trees; leaves petioled, commonly oblique at the base; 

 flowers axillary, solitary or few in a cluster, greenish. 



C. occidentalis, L. Young leaves and branchlets silky ; 

 leaves (2' long) ovate, acuminate, sharply serrate, abruptly 

 contracted at the base, soon smooth, ferruginous beneath ; 

 fertile floiuers mostly solitary, on drooping peduncles ; the 

 sterile ones 2-4 in a cluster ; drupe dark purple, with a thin 

 SAveet pulp. March. A tree, 40°-60° high. — Var., integri- 

 FOLIA. (0. integrifolia, Nutt.) Leaves ovate or ovate-lan- 

 ceolate (2-3' long), acuminate, entire, rounded, or the 

 lower ones cordate at the base, roughened with minute 

 elevated points. Sandy soil. A small tree; branches 

 and leaves 2-ranked. — Var., pumila. (C. pumila, Pursh.) 

 Shrubby ; leaves (1 -IJ' long) ovate, acute, serrate, obtuse 

 at the base, pale beneath, very rough above ; dr^ij^e glau- 

 cous. Shady woods. March and April. Stem 5°-10° 

 high. 



118. PLANE-TREE FAMILY. Order, Platanace.^. 



Large trees, with alternate palmately-lobed petioled 

 leaves, and moncecious flotvers, in axillary long-peduncled 



