146 ROSACK^. (rose family.) 



the two narrow valves separating on each side from a thickened margin. — Pc- 

 reiniiiil herbs, nearly related to the true Sensitive Phmts (Mimosa) ; tlie procum- 

 bent stems mid petioles prickly, with twice-jiinnatc sensitive leaves of many 

 small leafletij, and axillary peduncles bearing round heads of small rose-colored 

 flowers. (Named for F. P. Schrank, a German botanist.) 



1. S. uncinkta, Willd. Prickles hooked; partial petioles 4-6 pairs; 

 k-dfhts e//i/itiml, nticulakd with stiony veins Ijencath ; pods oblong-linear, nearly 

 terete, short-pointed, densely prickly (2' long). — Dry sandy soil, Virginia, 

 Illinois? and southward. June -Aug. 



2. S. angUSt^ta, Torr. & Gray. Leaflets oblonfj-linear, scarcehj veimd; -fodis 

 slender, tajier-poiuted, sparingly prickly (about 4' long). — With the preceding. 



Okdeh 33. ROSACEA. (Rose Family.) 



Plants with regular /lowers, numerous (rarely few) distinct stamens in- 

 sened on the calyx, and 1 - many pisiiU^ which are (/uite distinct, or (in the 

 Pear tribe) united and combined with the calyx-tnbe. Seeds (anatropous) 

 1 -few in each ovary, almost always without albumen. Embryo straight, 

 with large and thick cotyledons. Leaves alternate, with stipules, these some- 

 times caducous, rarely obsolete or wanting. — Calyx of 5 or rarely 3 - 4 - 

 8 sepals (the odd one superior), united at the base, often appearing double 

 by a row of bractlets outside. Petals as many as the sepals (rarely want- 

 ing), mostly imbricated in the bud, and inserted with the stamens on the 

 edge of a disk that lines the calyx-tube. Trees, shrubs, or herbs. — A 

 large and important order, almost destitute of noxious qualities, and pro- 

 ducing the most valuable fruits. Very intimately connected with Legu- 

 minosa; on one Land, and with Saxifragaceaj on the other. 



SuBOKDER I. AMYGDALJC^. (Almond Family.) 



Calyx entirely free from the (usually) solitary ovary, deciduous. Style 

 terminal or nearly so. Fruit a drupe (stone-fi-uit), 1-seeded, or rarely 2- 

 seeded. — Trees or shrubs, with simple leaves, the bark exuding gum, and 

 the bark, leaves, and kernels yielding the peculiar flavor of prussic acid. 

 Stipules free, often deciduous. 



1. Prunus. Flowers perfect. Lol)C3 of the calyx and petals .5. Stone of the drupe bony. 



Suborder II. KOSACEiE tropeu. 

 Calyx free from the ovaries (but sometimes enclosing them in its tube), 

 mostl)' persistent with the fruit. Pistils few or many, distinct, occasionally 

 single. Stipules commonly united with the petiole. 



Tribe I. fVlRJEEJE. Pistils mostly 5 and forming follicles in fruit: styles terminal. 

 Calyx without bractlets. Seeds not rarely with some albumen ! 



2. Splrren. Calyx 5-cleft, short. Petals obovate, equal, chiefly imbricated in the bud. 



3. Glllenla. CMyx elongated, 6-toolUed. PcUla slender, unequal, convolute in the bud. 



