WEATHERBY.— AMERICAN FORMS OF LYCOPODIUM COMPLANATUM. 413 
South American) are connected by various intermediates, but, in 
their extreme development, are sufficiently diverse to warrant varie- 
tal distinction. Indeed, since Humboldt and Bonpland described their 
Lycopodium thyoides in 1810, it has been recognized by most botanists 
that some, at least, of the tropical material differed from typical L. 
complanatum of northern Europe and North America; and L. thy- 
oides has been rather generally maintained as a variety, differently 
defined by different authors. Neither its relation to the northern 
forms, however, nor its exact identity in regard to the other tropi- 
cal form seems to have worked out with entire clearness. Lloyd and 
Underwood, in their Review of the North American Species of Lyco- 
podium,? called attention to the habital difference between Mexican 
and Central American, and northern specimens ; but, partly owing, no 
doubt, to their reluctance to describe varieties, carried their studies no 
further. Dr. Christ,? in a brief but clear note, has pointed out 
distinctions between the two southern forms; but he seems to be in 
error in referring the prevailing South American form to typical L. com- 
planatum. The plant of northern Europe and America which, as Prof. 
Fernald has shown, should be regarded as the type of the Linnaean 
species, is low, and habitally as well as in the characters of its branchlets 
and their leaves, quite different from the taller South American plant. 
Dr. Christ seems also to have been in error in identifying the other tropi- 
cal extreme, which has broad branchlets and long leaves with con- 
spicuously spreading tips, with L. thyoides H. & B. The original 
description of this species in Willd. Sp. Pl. v. 18, emphasizes rather 
strongly the appressed leaves. In view of the facts that the type 
specimens were from Venezuela, and that the appressed-leaved form is 
apparently much the more common throughout South America, it 
seems best to follow the first diagnosis, and to restrict L. thyoides 
to that form. : : 
In spite of their complete geographic separation, there 1s nothing to 
warrant the segregation of the tropical forms as separate e ad 
characters which distinguish them are of too little importance them- 
selves and too inconstant. They are rather to be considered as eX- 
treme developments of tendencies which are traceable also in occasional 
specimens of the northern plant, but are there not so strongly Se oa 
earliest varietal designation of the South American plant and that 
which, under the Vienna Rules, it should bear, 1s L. greg 
B tropicum Spring, based on L. thyoides H. & B. The other, prevail- 
ingly Mexican, extreme seems to be without an availablename. 
2 Bull. Torr. : xxvii. 165 (1900). > 
3 Bull. foe wae a 2, ii. 707 900). * “ foliis semper adpressis. 
