1920] Fernald & Wiegand,—Cerastiums of Section Orthodon 179 
ovate, flaccid to rigid, acute to obtuse, glabrous to velutinous, gland- 
less or glandular, 1-6 em. long, 0.5-13 mm. broad, mostly confined 
to the lower two-thirds of the branch: inflorescence few- to many- 
flowered, its bracts scarious-margined: sepals 4.5-8.5 mm. long, gla- 
brous, pilose or glandular: petals 2-3 times as long as the sepals; 
the broad lobes spreading in anthesis; the claw glabrous: capsule 
cylindric, equaling to much exceeding the calyx: seeds reddish, 
0.35-0.7 mm. in diameter, the testa close and tuberculate.—Sp. Pl. 
i. 438 (1753).—Rocky, gravelly or sandy habitats, chiefly in some- 
what calcareous or magnesian soils, widely dispersed in boreal regions, 
extending south in varying forms to Georgia, the Great Lake region, 
New Mexico and California; Eurasia and South America. 
We attempt no statement of bibliography and synonymy at present, 
since all our attempts to reduce the species-complex to definite species 
or varieties with natural ranges have proved futile. After carefully 
measuring sepals, capsules and seeds, and closely examining pubes- 
cence and foliage during two different periods of nearly two weeks | 
each we are forced to the conclusion that in North America the group 
is as unstable in these characters as in Europe where Willkomm found 
"varietates constantes vix distingui possunt." For instance, a 
characteristic plant of Pennsylvania and southern New York, which 
is variously treated as C. arvense, var. oblongifolium (Torr.) Holl. & 
Britt., C. oblongifolium Torr. and C. velutinum Raf., is commonly 
separated by its long capsule; but abundant collections, which by 
their discriminating collectors have been referred to this plant, show 
capsules no longer than in much of the material from Newfoundland 
or the Canadian Northwest, while many sheets of material collected 
as one plant show both long and short capsules; and many specimens 
uniform as to capsules show the greatest diversity in the size and 
remoteness of the leaves. In some areas essentially all the plants 
of the C. arvense series are quite glandular, in other closely adjacent 
areas glandless but villous, so that within a limited region it would 
be possible to subdivide C. arvense into variants of seeming stability, 
but throughout the broad range around the northern hemisphere 
these variable characters interchange so perplexingly that the writers 
find themselves at present unable to determine which of these fickle 
tendencies have real taxonomic value. They accordingly are leav- 
ing C. arvense as a perplexing, polymorphous species, not wholly 
abandoned but cheerfully commended to others who care to attack 
it and who by a new approach and prolonged study may perhaps 
reduce it to a series of tangible entities. 
