Log DR. R. R. GATES: A STUDY OF NORTH AMERICAN 
panicle of Stenanthium. It may suffice to point out that the traditional 
conception of gradual transition is based upon suppositions which require 
proof as much as do those of sharp steps. If crossing experiments between 
these two genera could be instituted, it might throw light on the nature of 
all these differences. 
11. STENANTHELLA, Rydb. 
The genus Stenanthella was segregated from Stenanthium by Rydberg, to 
contain the two species S. sachalinensis (F. Schmidt), Rydb., and S. occidentalis. 
To these should be added S. frigidum from Mexico, which stands much nearer 
to Stenanthella than to Stenanthium. The North-American species are then 
as follows :— 
1. STENANTHELLA OCCIDENTALIS (A. Gray), Rydb. 
S. occidentalis, Rydb. in Bull. Torr. Bot. Club, xxvii. (1900) 531. 
Stenanthium occidentale, A. Gray, in Proc. Amer. Acad. viii. (1872) 405. 
Alberta and British Columbia to Oregon and Montana, and south to Trinity 
Co., California. 
2. STENANTHELLA FRIGIDA (Schlecht. et Cham.), comb. nov. 
Veratrum frigidum, Schlecht. et Chamisso, in Linnea, vi. (1831) 46. 
Zigadenus frigidus, D. Don, in Edinb. N. Phil. Journ. (1832) 933. 
Stenanthium frigidum, Kunth, Enum, Plant. iv. (1843) 189. 
Mexico. 
In S. frigida the ovary is partly inferior, but this alone is not sufticient 
reason for separating it from ©. occidentalis, which it otherwise clearly 
resembles. It differs from the latter chiefly in its somewhat larger size, 
larger flowers, dark purple perianth, and shorter and less pointed capsules. 
The genus Stenanthella, which is markedly distinct from Stenanthium, 
differs mainly in the following characters :— 
Stenanthium. Stenanthella, 
Inflorescence a large panicle of many sessile Inflorescence a raceme of few flowers on 
flowers. long pedicels, 
Flowers polygamous, small, white or Flowers perfect, much larger, greenish, 
greenish, open, not campanulate. brownish, or purplish, campanulate. 
Tips of perianth-segments not reflexed. Tips of perianth-segments reflexed and 
finally involute. 
12. ZIGADENUS, Michaux. 
1. ZIGADENUS GLABERRIMUS, Michx. Fl. Bor. Am. i. (1803) 214, t. 22 ; Del. 
in Redouté, Lil. viii. t. 461 (1816) ; Rydb. in Bull. Torr. Bot. Club, 
xxx. (1903) 280, pl. 12. f. 1. 
Helonias glaberrima, Link, Enum, Hort. Berol. i. (1821) 348. 
In swamps, Virginia to Florida, and west to Mississippi, usually near the 
coast, 
