NET RS ASTE ONERE NR PEENE ET 
138 DR. R. R. GATES : A STUDY OF NORTH AMERICAN 
As already remarked, it agrees in habit with the species of Triantha, 
particularly T. racemosa, but differs sharply in two characters: (1) the 
absence of pubescence from the stem, (2) the flowers not arranged in threes. 
Its distribution is restricted, and it seems reasonable to conjecture that it 
may have originated from 7. racemosa by two mutations. At any rate, 
it appears to differ from that species by what may very well be two unit 
characters, one of them a “loss” character. Certain specimens of T. race- 
mosa from Carolina depart from the type in having the flowers for the most 
part not in threes but arranged as in 7. glabra. Some of these may perhaps 
be hybrids between Tojieldia glabra and Triantha racemosa, or possibly 
mutations from the latter. Breeding experiments with those two forms 
could be profitably inaugurated, and a study of the forms occurring in North 
and South Carolina should also be made. 
Triantha racemosa, which is more southern and much less widespread 
than T. glutinosa, differs from the latter mainly in (1) pubescence more 
scabrous, (2) perianth becoming rigid, (3) capsule firm, dark-coloured, long- 
beakel. Of the two western species, 7. intermedia is not very sharply 
marked. It is distinguished from T. glutinosa by (1) having a short, more 
or less globose raceme, not elongated as in the eastern species ; (2) having 
longer pedicels and oblong subequal perianth-segments (4 mm. long). 
T. occidentalis is somewhat more restricted in range than T. intermedia, from 
which it is distinguished by its narrower, less connate bractlets, longer 
pedicels, narrower sepals, larger capsules (8 mm. long), and longer ascending 
beaks. "These are all quantitative differences, not sharply marked. 
The third known species of Triantha, T. japonica, Baker, I have not seen. 
It is perhaps related to 7. intermedia. 
The three main differences between the closely related Tofieldia and 
Triantha—namely, (1) the arrangement of the flowers in clusters of three 
instead of singly on the stem, (2) the appearance of a characteristic rough 
pubescence, (3) the caudate seeds—are such as might have resulted from 
three mutations. But, if so, where are the forms exhibiting only a single one 
of these changes, and why have only the forms containing all three been 
preserved? There is perhaps no utility in any of these characters, but it 
would appear that only forms having all three of these features, or lacking 
them all, have survived. Yet to suppose the passage from Tojieldia to 
e , à : ; 
Triantha in a single step requires a much larger change than we know from 
experience. These are but a few of the questions raised by a consideration 
of the two genera. 
3. PLEEA, Michaux. 
PLEEA TENUIFOLIA, Michx. Fl. Bor. Am. i. (1803) 248, t. 25; Delar. in 
Redonté, Lil. v. (1809) t. 248; Sims, in Bot. Mag. (1818) t. 1956. 
In pine-land swamps, S. Carolina to Florida. 
