622 MISC. PUBLICATION 4 2 3, U. S. DEPT. OF AGRICULTURE 

 4. EPILOBIUM" Willow-weed 



Plants annual or perennial, herbaceous; leaves nearly or quite 

 sessile; flowers axillary or in terminal racemes or panicles; hypan- 

 thium either short or not prolonged beyond the ovary; sepals 4; 

 petals 4, usually notched, white, pink, or purplish; stamens 8, the 

 alternate ones shorter; capsule elongate, subcylindric to clavate, 

 4-celled, loculicidal. 



Key to the species 



1. Hypanthium not prolonged beyond the ovary; flowers large; petals 8 to 18 



mm. long, entire, spreading 1. E. angustifolium. 



1. Hypanthium prolonged beyond the ovary; flowers smaller; petals 2 to 6 mm. 



long, notched, ascending (2). 



2. Plants annual, of dry situations; stems with an exfoliating epidermis (3). 



3. Stems glabrous except in the upper parts, usually more than 30 cm. 



long; leaves usually alternate, with fascicles in the axils; hypanthium 



1 to 3 mm. long 2. E. paniculatum. 



3. Stems puberulent throughout, less than 30 cm. long; leaves mostly 



opposite, without fascicles; hypanthium scarcely 1 mm. long. 



3. E. MINTJTUM. 



2. Plants usually perennial, mostly of moist situations; epidermis of the stems 

 not exfoliating (4). 



4. Rootstocks bearing turions, i. e., globose or ovoid winter buds with fleshy 



overlapping scales (5) . 

 5. Leaves lanceolate, appressed-erect, sharply denticulate. 



4. E. HALLEANUM. 



5. Leaves lance-ovate to ovate, ^ spreading, subentire to denticulate. 



5. E. SAXIMONTANUM. 



4. Rootstocks not bearing turions (6). 



6. Plants cespitose, 1 to 2 dm. high, from a matted base; stems simple 



above 6. E. hornemamii. 



6. Plants 1- to few-stemmed, 3 to 6 dm. high; stems branched above (7). 



7. Inflorescence glandular-pubescent 7. E. adenocaulon. 



7. Inflorescence whitish-pubescent, not glandular. 8. E. californicum. 



1. Epilobium angustifolium L., Sp. PL 347. 1753. 



Chamaenerion angustifolium Scop., Fl. Cam. ed. 2, 1 : 271. 1772. 



Kaibab Plateau and San Francisco Peaks (Coconino County), to 

 the mountains of Greenlee and Graham Counties, 7,000 to 1 1,000 

 feet, damp places, July to August. Widely distributed in the North- 

 ern Hemisphere. 



Fireweed, blooming-sally. The large rose to almost lilac flowers, 

 strongly perennial habit, and elongate capsules opening to expose 

 masses of dingy coma are characteristic. 



2. Epilobium paniculatum Nutt. ex Torr. and Gray, Fl. North Amer. 



1: 490. 1840. 

 A polymorphous species of wide distribution in the western United 

 States, occurring in Arizona in the following forms: (1) f. adenocladon 

 Hausskn., with capsules and pedicels glandular-puberulent and petals 

 rose to lilac, 5 to 7 mm. long, Coconino, Yavapai, and Gila Counties, 

 dry, open and disturbed places, 5,000 to 8,500 feet, August to Oc- 

 tober; (2) f. subulatum Hausskn., with capsules and pedicels glabrous 

 and petals as in the preceding, Coconino and Yavapai Counties; (3) 

 f. tracyi (Rydb.) St. John, with petals white, 2 to 3 mm. long, and 

 capsule subglabrous, Kaibab Plateau, at Nagle Ranch, 7,600 feet 

 (Jones 6054i), and Jacobs Lake, 8,050 feet (Kearney and Peebles 

 13662). 



91 Reference: Trelease, Wm. the species of epilobium occurring north of mexico. Mo. Bot. 

 Gard. Ann. Rpt. 2: 69-117. 1891. 



