SALICACEAE (WILLOW FAMILY) 127 



1. Corallorhiza multiflora Nutt. Journ. Acad. Phil. 3: 138. pi. 7. 1823. 

 Scape 2-5 dm. high, many-flowered: flowers brownish-purple: sepals and 

 petals 3-nerved; spur manifest, but wholly adnate to the ovary; lip nearly 

 sessile, 3-lobed by a deep cleft on each side, the middle one rounded or emar- 

 ginate, with undulate or denticulate margin: capsule 10-14 mm. long, nar- 

 rowed to a short rather stout pedicel. (C. ochroleuca Rydb. Bull. Torr. Bot. 

 Club 31: 402. 1904.) Across the continent in north temperate latitudes, and 

 in the Rocky Mountains southward to Utah and Colorado. 



2. Corallorhiza innata R. Br. in Ait. Hort. Kew, Ed. 2. 5: 209. 1813. 

 Scape slender, 1-2 dm. high, 3-15-flowered: sepals and petals 1-nerved, dull 

 purple; spur very short; lip somewhat 3-lobed by lateral clefts, abruptly at- 

 tenuate to the base; column stout, constricted in the middle: capsule 4-8 mm. 

 long, abruptly narrowed to a short very slender pedicel. From Colorado to 

 Washington and thence eastward to Canada and the Atlantic States, and 

 northward to the Arctic regions. 



3. Corallorhiza striata Lindl. Gen. & Sp. Orch. 534. 1840. Scape stout, 

 3-6 dm. high, many-flowered: flowers often 12-15 mm. long: spur none, the 

 lateral sepals and base of the column strongly gibbous over the top of the 

 ovary: flowers larger, purple and veined, not spotted: lip fleshy, entire, some- 

 what narrowed below, reflexed above the base and bearing the prominent 

 laminae upon the arch. (C. Vreelandii Rydb. 1. c. 8: 271. 1901.) From 

 Washington and Oregon eastward to the Great Lakes. 



28. SALICACEAE Lindl. WILLOW FAMILY 



Trees and shrubs with simple, alternate, stipulate leaves. Flowers dioe- 

 cious, arranged in aments (catkins), these falling off as a whole, the staminate 

 after anthesis, the pistillate after the ripening of the fruit and dispersion of 

 the seeds. Bracts of the ament scale-like. Perianth none. Stamens 1 to 

 several. Ovary 1-celled; stigmas 2. Fruit a 2-valved capsule, inclosing many 

 seeds furnished with a tuft of hairs at base. 



Bracts lacerate; flowers with a broad or cup-shaped disk; stamens numerous; 



buds scaly . . . . . . . . . . . .1. Populus. 



Bracts entire; flowers with small glands; disks none; stamens few; buds with 



a single scale 2. Salix. 



1. POPULUS L. POPLA.R. COTTONWOOD. ASPEN 



Deciduous dioecious trees, often low, with pale furrowed bark, and terete 

 or angular branchlets. Leaves varying from broadly deltoid-cordate to 

 narrowly lanceolate. Buds scaly, usually covered with a resinous varnish. 

 Both kinds of flowers in drooping aments appearing before the leaves; bracts 

 lacerate. Flowers with a broad or cup-shaped disk. Stamens numerous. 

 Stigmas elongated. Fruit a dehiscent capsule with many seeds, each bearing 

 a tuft of white hairs. 



Petioles flattened laterally. 



Leaves suborbicular 1. P. tremuloides. 



Leaves broad, more or less deltoid. 



Abruptly acuminate, crenately serrate . . . . . . 2. P. occidentalis. 



Gradually acuminate, deeply sinuate-dentate . . . . 3. P. Wislizenii. 



Petioles round or furrowed. 



Leaves pale beneath . . . . . . . . . 4. P. balsamifera. 



Leaves green, scarcely lighter beneath. 



Oblong-lanceolate . . . . . . . . . 5. P. angustifolia. 



Ovate, abruptly long-acuminate 6. P. acuminata. 



1. Populus tremuloides Michx. Fl. Bor. Am. 2: 243. 1803. A small tree, 

 6-20 m. high, usually in dense groves and rarely attaining the maximum size; 

 bark smooth, greenish- white : leaves small, roundish heart-shaped, with a 



