FLORA OF THE DISTRICT OF COLUMBIA. 173 



2. LIQUIDAMBAR L. 



1. Liquldambar styracifl.ua L. Sweet gum. 



Moist woods; frequent. May. Southern states, north to Conn. 



78. PLATANACEAE. Sycamore Family. 



1. PLAT anus L. 



1. Platanus occidentals L. Sycamork. 



"Rich or moist woods; frequent. May. Eastern U. S. 



79. ROSACEAE. Rose Family. 



Plants shrubby. 

 Loaves simple; fruit a follicle or pod with several seeds; plants not prickly. 



Follicles inflated ; leaves palmately nerved and lobed 1 . OPULASTER . 



Follicles not inflated ; leaves pinnately veined , not lobed 2. SPIRAEA . 



Leaves compound; fruit of achenes (several within a fleshy receptacle) or a cluster 

 of drupelets; plants armed with prickles. 

 Leaves pinnately compound; fruit of several bony achenes or nutlets inclosed in a 

 globular or pear-shaped, somewhat fleshy receptacle; flowers pink, some- 

 times fading to nearly white 3. ROSA. 



Leaves palmately compound; fruit a globular or oblong cluster of drupelets; 

 flowers white, sometime* becoming pinkish with age, rarely purplish red. 



4. RUBUS. 

 Plants herbaceous. 

 Pistil containing more than 1 ovule; fruit a follicle. 



Leaves 2-3- pinnate; flowers small, in a large spieate pauicle 5. ARUNCUS. 



Leaves 3-foliolate; flowers few, long-peduncled 6. PORTERANTHUS. 



Pistil 1-ovuled; fruit an achene, the receptacle sometimes fleshy. 

 Receptacle enlarged in fruit, juicy or spongy. Plants with runners; leaves 

 3-foliolate. 



Petals white; fruiting receptacle juicy 7, FRAGARIA. 



Petals yellow; fruiting receptacle spongy 8. DUCHESNEA, 



Receptacle not enlarged in fruit. d*y. 

 Achenes numerous, upon a convex receptacle. 



Styles elongating in fruit, jointed and bent near the middle, the upper part 



deciduous, the lower persistent as a hook 9. GEUM. 



Styles not elongating in fruit and not forming hooks... 10. POTENTILLA. 

 Achenes few, inclosed in an um-slmpod calyx tube. 



Petals present, yellow; flowers in long racemes. Margin of the top-shaped 



fruiting calyx with hooked prickles 11. AGRIMONIA. 



Petals absent; flowers clustered or spieate. 



Flowers in small, nearly sessile clusters; planta low annual. . 12. APHANES. 

 Flowers in long-peduncled dense heads or spikes; plants perennial. 

 Inflorescence cylindric, white; leaflets 2-5 cm. long. 



13. SANGUISORBA. 

 Inflorescence globular, green; leaflets 8-15 mm. long.. 14. POTERITJM. 



1. OPULASTER Medic. 



1. Opulaster opulifohus (L.) Kuntze. Nine-bark. 



Rocky woods; frequent. May. Eastern U. S. (Physocarpus opvhfnJws Maxim.; 

 Neillin opuli/olia Benth. & Hook.) 



