22 Contributions from the Gray Herbarium 
thin and elongated root from which branch a number of tough 
rather slender rootlets. In other species (V. cordifolia, for example) 
the root becomes very thick, vertical, and subfusiform or napiform, 
being sometimes as much as 3 dm. long by 3 cm. thick. In others, 
as in V. Kunthiana, it is slender and vertical. In some South 
American species, such as V. fusiformis and V. tuberosa, the root is 
thick, woody, and tuberous, bearing a cluster of slenderly fusiform 
rootlets. In V. squalida, and probably in all its near relatives of 
the series Grandiflorae, there is a thick, short root, about 2 cm. 
long, bearing a cluster of slender rootlets. V. decurrens and some 
other species of Mexico have a horizontal very woody rootstock, 
at least 13 cm. long, bearing on the upper side the bases of old stems 
and on the under several thickened tuberlike roots, some of which 
nearly equal in size the main rootstock itself. 
Stems and Branches. The stem of all Viguieras is normally 
terete in section, obscurely or distinctly striate, and usually pubes- 
cent with harsh hairs. In internal structure the stems show all 
gradations in various species between the very herbaceous type 
found in the annuals of the section Diplostichis and the very woody 
extreme found in V. brevifolia, in which the woody cylinder makes 
up nearly the whole substance of the stem and the pith is very 
greatly reduced. 
Leaves. As in most of the large genera of Heliantheae, the species 
of Viguiera show great variation in the form, texture, and toothing 
of their leaves, when the genus is considered as a whole, while the 
variations in a single species may be slight or so great as to have 
given ground in the past for the description of several species now 
shown by full series of specimens to be too completely intergradi- 
ent for independent recognition (see especially V. dentata (no. 36) 
and V. deltoidea (no. 39)). The typical or synthetic leaf of the genus 
may be described in general terms as ovate, acute or acutish, tTip- 
linerved and more or less toothed. This type of leaf is shown by 
many of the large series Awreae of South America, which there 18 
reason to believe represent most nearly the ancestral stock of the 
genus, as well as by many other species of various groups. Ex- 
tremes of variation are found in V. decurrens, with sessile strongly 
decurrent ovate leaves, the largest in the genus, on the one hand, 
and on the other in the section Trichophylla, with strongly revolute 
very narrowly linear or linear-filiform leaves. 


