146 ROSACEA. (ROSE FAMILY.) 



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

 rennial herbs, nearly related to the true Sensitive Plants (Mimosa) ; the procum- 

 bent stems and petioles prickly, with twice-pinnate sensitive leaves of many 

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

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



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

 leaflets elliptical, reticulated with strong veins beneath ; pods oblong-linear, nearly 

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

 Illinois ? and southward. June - Aug. 



2. S. angUStata, Torr. & Gray. Leaflets oblong-linear, scarcely veined ; pods 

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



Order 33. ROSACEA. (Rose Family.) 



Plants with regular flowers, numerous {rarely few) distinct stamens in- 

 serted on the calyx, and 1 - many pistils, which are quite distinct, or (in the 

 Pear tribe) united and combined with the calyx-tube. 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- 

 minosae on one hand, and with Saxifragaceae on the other. 



Suborder I. AMYGDALEJ1. (Almond Family.) 



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

 terminal or nearly so. Fruit a drupe (stone-fruit), 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. Lobes of the calyx and petals 5. Stone of the drupe bony. 



Suborder II. ROSACEA proper. 



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

 mostly persistent with the fruit. Pistils few or many, distinct, occasionally 

 single. Stipules commonly united with the petiole. 



Tribe I. SPIRiEE^. Pistils mostly 5 and forming follicles in fruit : styles term inaL 

 Calyx without bractlets. Seeds not rarely with some albumen ! 



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



3. Gillenia. Calyx elongated, 5-toothed. Petals slender, unequal, convolute in the bud. 



