112 ROSACEA. 



aestivation. Petals perigynous, as many as the calyx-lobes and alternate 

 with them, or 0. Stamens 5 — oo , perigynous. Pistils 1 — oo ; ovary usually 

 1-celled and with 1 ovule, sometimes many-ovuled: ovules pendulous or 

 ascending. Styles as many as the ovaries. Fruit an achene or an 

 aggregation of drupelets, sometimes follicular and dehiscent by the 

 ventral suture. Seeds with little or no albumen. 



* Unarmed shrubs: leaven simple. 



Pistils 3 — 5; mature carpels dry, dehiscent, 



inflated, Beveral-seeded, Opulaster 1 



not inflated, 1-eeeded, Holodisous 2 



p. ... n ( fruit a plumo3e-tailed achene Cebcooarpus 3 



( fruit an achene without plumose tail Adenostoma 4 



* * Prickly shrubs. 



Fruit a mass of coherent drupelets, Rubtjs 10 



Fruit a number of bony achenes, enclosed 



in a red berry-like calyx-tube Rosa 11 



* * * Herbaceous plants; mostly perennial. 



Leaves unequally pinnate; pistil I only; 



Fl. apetalouB; mature calyx-tube beset with 



retrorsely barbed prickles AcraxA 5 



Mature calyx bur-like with hooked prickles ActRiMONIA 6 



Leaves variously compound or cleft; pistils several 



or many; fruits achenes; 

 Small annuals, with minute green 



apetalous flowers, and only 2 pistils Alchemill A 7 



Leaves palmate or pinnate; pistils oo ; 



achenes on a dry usually hairy receptacle, Potentilla 8 



Leaves ternate; pistils ao; achenes on a conical 



fleshy receptacle, Fragakia 9 



1. OPCL ASTER, Medic. (Nine-Bark). Shrubs unarmed with sur- 

 culose shreddy-barked stems and simple more or less lobed and toothed 

 deciduous leaves ; stipules free and deciduous. Flowers white, in corymbs 

 terminating lateral leafy branchlets. Calyx 5-lobed with campanulate 

 tube. Petals 5, rounded. Stamens oo , in several rows. Pistils 1—5, 

 becoming as many inflated 2-valved several-seeded capsules which are 

 alternate with the calyx-lobes when of the same number, slightly coherent 

 toward the base. Seeds several, obovoid, with a shining crustaceous 

 testa, and copius albumen. 



1. 0. capitatns (Pursh). Surculiform stems 10—20 ft. long, more 

 or le3S tortuous and reclining or interlacing among the branches of 

 small trees: leaves short-petioled, ovate, acute, more or less distinctly 

 3-lobed and coarsely toothed, 2—3 in. long, glabrous or stellate-pubescent: 

 fl. in hemispherical corymbs: pedicels and calyx more or less tomentose: 

 follicles usually 4, exceeding the calyx, 3-4 lines long,, ultimately 

 splitting into 2 valves.— Common along streams. April, May. 



