ROSE FAMILY 161 



1910-1911). Smith, C. P., Studies in the genus Erythrocoma (Muhl. 8:1-17, pis. 1-3,-1912). 

 Palmer, E. J., Synopsis of N. Am. Crataegi (Jour. Arnold Arboretum 6:5-128, — 1925). Darrow, 

 G. M., Development of runners and runner plants in the strawberry (U. S. Dept. Agr. Tech. Bull. 

 ] 22: 1-28, figs. 1-14,-1929). 



A. Ovary superior. 



1. Fruit dehiscent, consisting op 2 to 5 dry pods or follicles; trees, 

 SHRUBS OR herbs. — Tribe Spiraeae. 



Flowers perfect; trees or shrubs. 



Calyx-lobes deciduous; leaves opposite; trees 1. Lyonothamnus. 



Calyx-lobes persistent; leaves alternate; shrubs. 

 Stamens distinct; erect shrubs. 

 Leaves simple. 



Pods inflated, 2 to 4-seeded; flowers white 2. Physocarptts. 



Pods not inflated. 



Stamens well exserted; flowers mostly rose-color; pods several-seeded, 



dehiscent 3. Spiraea. 



Stamens scarcely exserted; flowers creamy-white; pods 1-seeded, tardily 



dehiscent or indehiscent 4. HOLODISCUS. 



Leaves compound, the leaflets minute 5. Chamaebatiaria. 



Stamens united at base ; leaves dissected ; decumbent shnib 6. Luetkea. 



Flowers dioecious ; tall herb 7. Arxtncus. 



2. Fruit indehiscent; shrubs or herbs. 



a. Ovary becoming an achene (or drupelet in no. 8). — Tribe Eoseae. 



Pistils more than 1, commonly many to numerous; achenes more than 1. 



Pistils becoming drupelets which are coherent on a convex receptacle and form a fruit called 



a "berry"; leaves compound or simple; shrubs or bushes 8. EuBUS. 



Pistils becoming dry achenes; leaves compound, or pinnately lobed. 

 Pistils borne on a flat or convex receptacle. 

 Bractlets present. 



Style deciduous from the achene; receptacle conic; herbs (except one species 

 in no. 10). 



Eeceptacle fleshy ; leaves 3-foliolate 9. Fragaria, 



Eeceptacle dry; leaves pinnate or palmate, the leaflets 4 to numerous, 



rarely 3 10. Potentilla. 



Style persistent on the achene. 



Leaves pinnately compound; receptacle conic or hemispheric; achenes and 



styles strongly deflexed ; herbs 11. Geum. 



Leaves simple, pinnately lobed; receptacle flat; achenes and styles not de- 

 flexed ; shrubs 12. Fallugia. 



Bractlets wanting; achene with a long feathery tail; leaves pinnately lobed; shrub.. 



13. CoWAiJIA. 



Pistils disposed on the inside of a globose or urnshaped calyx-tube which is lined by a 



thin disk or receptacle, in fruit termed a "hip"; leaves pinnate; stems prickly.. 



14. EoSA. 



Pistil only one. 



Leaves compound. 



Low bush; leaflets numerous, minute 15, Chamaebatia. 



Herbs. 



Leaves pinnate. 



Calyx prickly; perennials. 



Petals yellow; prickles of calyx hooked at tip 16. Aqrimonia. 



Petals none; prickles of calyx straight but retrorsely barbed.. 17. Acaena. 



Calyx not prickly; petals none; annuals or perennials 18. Sanguisorba. 



Leaves palmately divided ; petals none ; diminutive annuals 19. Alchemilla. 



Leaves simple; shrubs. 



Achene with long feathery tail; petals none 20. Cercocarpus.. 



Achene not tailed ; leaves small, mostly fascicled. 

 Leaves entire, narrow. 



Petals white ; loaves needle-like ; branches not spinescent 21. Adenostoma. 



Petals none; leaves narrowly oblanceolate; branches spinescent 



22. Coleogyne. 

 Leaves cuneate, 3-toothed or -lobed above; petals pale yellow 23. Purshia. 



