Blake — A Revision of the Genus Viguiera 23 
One special modification of leaf-form, frequent in the genus, 
deserves special mention. V. trachyphylla may be selected to illus- 
trate this (see t. 3. f. 19). In this species the large opposite leaves 
are ovate, abruptly contracted below into a broad sessile or sub- 
sessile base about 2 cm. long and nearly as wide, and the two promi- 
nent lateral veins arise 2-3 cm. above the apparent base of the 
leaf-blade. This peculiar venation, in connection with the very 
weak submarginal nerves in the portion below the contraction, 
shows that the morphological blade of the leaf is the portion above 
it, and the part below it a broadly winged petiole only the lowest 
part of which is naked. A somewhat similar condition is shown by 
several species of this and other groups (t. 3. f. 21) and in a very 
marked degree by V. rhombifolia (t. 3. f. 20) of the related series 
Grammatoglossae. Of special interest in this connection, as furnish- 
ing a complete series of leaf-forms showing the evolution of this 
character, is the not very distantly related Simsia amplexicaulis 
(Cav.) Pers., a member of the same subtribe (Verbesininae). In 
this species the thin ovate leaf is in young or poorly developed 
forms subtruncate or cuneate at base, the two lateral veins arising 
from the midrib approximately at the base of the lamina, which 
continues as a narrow wing on the upper portion of the slender 
petiole, and in well developed leaves to the base of the petiole 
where it expands into a prominent herbaceous auricle. On the 
upper leaves of nearly all specimens, and on the lower leaves of 
some, this herbaceous margin of the petiole becomes so broad that 
the leaf appears to be sessile with an abrupt contraction below 
the middle. In the related Simsia megacephala Sch. Bip. this con- 
_ dition is a fixed one for even the middle leaves, the two prominent 
lateral veins arising 2-4 cm. above the apparent base of the leaf, 
the deltoid lamina being abruptly contracted near the level of these 
lateral veins into a broadly margined base (petiole) about 1.5 em. 
wide above and as much as 3.7 cm. wide at base. 
Inflorescence. The inflorescence of Viguiera is uniformly de- 
terminate, in its simplest form confined to solitary heads terminat- 
ing the stem, and branches if present, by the production of axillary 
heads becoming obracemose, and by multiplication of heads and 
reduction of pedicels developing a distinctly cymose panicle. 
With few exceptions, which are noted in the systematic portion 
of this revision, the form of the inflorescence is of very little value 
in the genus for the recognition of groups above the species. 
