154 American Midland Naturalist Monograph No. 2 



4. Leaflets not rugose or strongly reticulate; sepals more or less glandular 

 on the back; native species. 



5. Tall shrubs 1-2 m. high. 



6. Hypanthium glandular-setose; leaflets closely serrulate, acute at 

 each end; stipules narrow, more or less involute; prickles straight 

 or usually more or less curved, flattened at the base; moist 

 thickets, or swampy ground, local. June-July. \_R. Carolina of 

 auth., not L.] Swamp Rose R. palustris Marsh. 



6. Hypanthium usually smooth; stipules flat; leaflets sharply serrate; 



branches usually without prickles; thickets and open woods, 



local. May-June. Meadow Rose R. blanda Ait. 



5. Low shrubs 20-75 cm. tall; leaflets rather coarsely serrate; prickles 

 straight, or none. 



7. Stems woody; leaflets 5 or 7; dry soil along roads or edges of 



woods; the common species throughout 111. May-July. \R. 

 humilis Marsh.} Pasture Rose R. Carolina L. 



7. Stems semi-herbaceous, weak and bristly; leaflets usually 9, some- 

 times 7 or 11; roadsides and hedgerows, chiefly in n. and centr. 

 111. June-July. [R. pratincola sensu Greene, non A. Br.; R. 



heliophila Greene} R. suffiilta Greene 



4. Leaflets rugose, thick, strongly reticulate, dark green above, grayish 



pubescent beneath; sepals 2.5-3 cm. long, tomentose, not glandular; 



pedicels velutinous; shrub 1-2 m. tall, the branches densely prickly 



and bristly; roadsides, escaped from cult.; native of e. Asia 



R. rugosa Thunb. 



13. Amelanchier Medic. — Shadbush. Serviceberry 



1. Blades short-acuminate or decidedly acute; petals 12-18 mm. long; trees or 

 tall shrubs. 



2. Young leaves and racemes densely white-tomentose, soon glabrous; sepals 

 triangular, acute; fruit somewhat dry and mealy, insipid and falling 

 early; lowest fruiting pedicels 1-2.5 cm. long; wooded hillsides and 

 banks throughout 111., not uncommon. Apr.-May [A. canadensis sensu 

 auth., non L.} A. arborea (Michx. f.) Fern. 



2. Young leaves and racemes nearly or quite glabrous from the first; sepals 

 lanceolate, acuminate; fruit sweet and juicy; lowest fruiting pe:^icels 



mostly 2.5-5 cm. long; wooded hillsides, n. 111. Apr -Mav 



A. laevis Wieg. 



1. Blades rounded at the apex, or merely acuti.sh or mucronate, oval, tomentose 

 beneath at flowering time; petals 7-10 mm. long; shrubs 05-1.5 m. tall; 



rocky or sandy soil, n. 111. May. [A. hutnilis Wieg.] Low Shadbush 



A. spicata (Lam.) K. Koch 



14. Sorbus L. — Mountain-ash 



1. Winter-buds densely whitish villous, 5-10 mm. long; leaflets elliptical, acute, 

 3-5 cm. long; flowers 8-9 mm. broad; fruits 9-11 mm. in diameter; native 

 of Eur., cult., and occasionally escaping to woods or roadsides. European 



