28 General Key to the Families 



XLVIII. ONAGRACE^. EVENING PRIMROSE FAMILY 



Herbaceous or shrubby plants ; leaves entire or toothed, alternate 

 or opposite; flowers axillary or in terminal spikes, perfect, sym- 

 metrical, calyx-tube adnate to the ovary, its lobes valvate in the 

 bud or obsolete, petals convolute in the bud, sometimes wanting; 

 fruit a many-seeded pod, seeds mostly silky-tufted. 



I. Epilobium. L. 



1. E. alpinum. L. Alpine Willow-herb. 



2. E. angustifolium. L. Great Willow-herb. 



3. E. lati folium. L. Water Willow-herb. 



4. E. anagallidifolium. Lam. Mountain Willow-herb. 



5. E. Hornemanni. Reichenb. Hornemann's Willow- 



herb. 



6. E, paniculatum. Nutt. Panicled Willow-herb. 



7. E. clavatum. Trel. Few-flowered Willow-herb. 



8. E. adenocaulon. Haussk. Northern Willow-herb. 



9. E. luteum. Pursh. Yellow Willow-herb. 

 XL CEnothera. L. 



I. O. biennis. L. Common Evening Primrose. 

 III. CiRC^A. (Tourn.) L. 



1. C. pacifica. Asch. and Mag. Pacific Enchanter's 



Nightshade. 



2. C. alpina. L. Small Enchanter's Nightshade. 



XLIX. HALORAGIDACE^. WATER MILFOIL FAMILY 



Aquatic or marsh plants ; leaves various, crowded, often whorled ; 

 flowers inconspicuous, symmetrical, sessile in the axils of the leaves 

 or bracts ; fruit dry and indehiscent, with a single anatropous seed 

 suspended from the summit of each cell. 



I. Myriophyllum. (Vaill.) L. 



I. M. spicatum. L. Spiked Water Milfoil. 

 II. HippuRis. L. 



I. H. vulgaris. L. Bottle Brush. 



3. H. montana. Ledeb. Mountain Mare's Tail, 



