Jones: Flora of Illinois, 83. Rosaceae 149 



19. Style persistent on the achene, jointed or plumose 8. Ceiitn 



18. Pistils 1-3; sepals 4, petaloid; petals none; achene usually solitary, 

 enclosed in the 4-angled calyx-tube; flowers (in our species) white, 

 in a dense cylindrical spike 9. Sanguisorba 



1 7. Calyx-tube with hooked bristles; flowers yellow, in spike-like racemes; 

 achenes 2 10. Agrimonia 



1. Physocarpus Maxim. 



(Opiilaster Medic; Phvsocarpa Raf.) 

 P. opulijolius (L.) Maxim. Ninebark. River banks, local, n. III. May- 

 June. Carpels 3-5, glabrous or pubescent. [P. intermedius (Rydb.) Schneid.J 



2. Spiraea L. 

 1. Leaves tomentose beneath; sepals reflexed; wet ground. July-Aug.; known to 



occur in Lake, Cook, Kankakee, and Iroquois counties. Hardback 



S. tomentosa L. 



L Leaves glabrous or nearly so beneath; sepals spreading or erect; moist 

 ground. July-Aug. \_S. salicijolia of auth., not L.] S. alba DuRoi 



3. Aruncus Adans. — Goat's-beard 

 A. dioicus (Walt.) Fern. Wooded ravines. May- June. Of local occurrence 

 throughout most of III., but apparently absent from the n. part of the state. 

 [^Aruncus aruncus of auth., not Spiraea aruncus L.; A. Sylvester of auth., not 

 Kostel.; A. pubescens Rydb.; A. allegheniensis Rydb.] 



4. GiLLENiA Moench — Indian Physic 

 G. stipidata (Muhl.) Trel. American Ipecac. Rich woods; extending 

 northw. to La Salle Co., more frequent southw. June- July. 



5. Fragaria L. — Strawberry 



L Robust, thick-leaved garden plants, often 20-40 cm. tall, sometimes escaped 

 from cult.; petals 9-12 mm. long; fruit ovoid-globose, 2-3 cm. in diameter; 



achenes set in shallow pits; roadsides and waste places. May 



F. chUoensis Duch. var. ananassa (Duch.) Hort. ex Bailey 



1. Native wild plants; fruit 6-15 mm. in diameter; plants usually smaller. 



2. Leaflets firm, dull green above, petiolulate; flowers in corymbs; petals 5- 

 10 mm. long; fruit ovoid or subglobose, 1-1.5 cm. in diameter at matur- 

 ity, the achenes set in pits; calyx-lobes not reflexed; grassy banks and 

 roadsides, or in open woods, very common. Apr.-June. [F. grayana 

 Vilm.] Wild Strawberry F. virginiana Duch. 



2. Leaflets thin, light green, subsessile; inflorescence irregular, the branches 

 unequal; petals 3-6 mm. long; fruit ovoid or conical, 6-9 mm. in diam- 

 eter, 1-1.5 cm. long, the calyx-lobes spreading or reflexed; achenes super- 

 ficial; rocky banks and open woods, n. III., local. May-June 



F. americana (Porter) Britt. 



6. POTENTILLA L. — Cinquefoil 



1. Shrubs 30-100 cm. tall, the bark shreddy; leaflets 5-7, elliptical, 1-2 cm. long, 

 silky-pubescent, the margins entire, revolute; flowers 1.5-3 cm. broad, yel- 



