1917] 
GATES—THE GENUS TRILLIUM 51 
may be greenish, yellowish, white, or pink, and they also vary 
in width. In the Napa Valley mostly the white-flowered form 
occurs. The anthers are yellow. 
Т. chloropetalum Howell, of Oregon and northern Cali- 
fornia, differs markedly in having oblanceolate, obtuse, white, 
erect petals 3—4 lines wide and should therefore probably re- 
ceive a new and distinct specific name. It is represented by 
the following specimens: 
California: Scott River, Siskiyou Co., April 25, 1910, Geo. 
D. Butler 1242 (Mo. Bot. Gard. Herb.) ; Humbug Creek, April 
3, 1910, Geo. D. Butler 1168 (Mo. Bot. Gard. Herb.), petals 5 
em. long, 15 mm. wide, obtuse; near Hupa, Humboldt Co., 1902, 
Mrs. М. Н. Manning (Univ. Cal. Herb., 30093) ; near Arcata, 
Humboldt Co., April 2, 1905, Joseph P. Tracy 2155 (Univ. Cal. 
Herb., 146219) ; Buck Mountain, Humboldt Co., June 17, 1913, 
J. P. Tracy 4181 (Univ. Cal. Herb., 175295). 
In some cases the petals are purple except near the base, 
as in the following specimens: 
California: Loma Prieta, eastern slope, April 4, 1894, 
J. B. Davy 468 (Univ. Cal. Herb., 4014) ; Olema, Marin Co., 
March 31, 1894, J. B. Davy 679 (Univ. Cal. Herb., 4015). 
Occasionally the petals are purple only at the tip. 
Crystal Springs Lake, San Mateo Co., March 30, 1902, 
C. F. Baker 431, the collector remarks: ‘‘This white or 
pinkish flowered Trillium is the predominant form in moist 
thickets about the lake, but few purple flowered Trilliums 
being seen here." The petals are also narrow, as in Ше 
typical var. chloropetalum. 
14b. Var. angustipetalum (Torr.) Gates, comb. nov. 
Plate 8. 
Т. sessile var. angustipetalum Torr. Рас. Rail. Rept. 4: 151. 
1856. 
The variety angustipetalum of Torrey apparently occurs 
as a variation throughout the range of the species. In other 
words, the petals vary in width from 2 mm. to 32 mm., and 
the variation is apparently continuous. Torrey characterized 
the variety as follows: ‘‘foliis basi subito contractes; petalis 
