6 Contributions from the Gray Herbarium 
PRELIMINARY Kry TO VIGUIERA AND IMMEDIATELY RELATED GENERA 
a. Achene not corky-margined, b. 
ppus present, c. 
c. Involucre 2-7-seriate, of more than 5 phyllaries, d. 
d. Pappus quickly deciduous; squamellae very rarely 
WRG oc eee ee ee HELIANTHUS L. 
d. Pappus persistent; squamellae always present, e. 
BIG bs, piace kee ae ch a ct TITHONIA Desf. 
e. Peduncles not swollen, or only slightly so; pales 
not stiff and prickly in fruit, f. 
f. Pappus of two awns and several short dis- 
tinctly thinner and more scarious squa- 
Fs Cua at tame ae ey SL wns VIGUIERA HBK. 
are cos ig RIE a Oe oe RAMS Ie HAPLOCALYMMA Blake. 
Rien Ge ee eee HELIOMERIS Nutt. 
a. Achene corky-margined ................. SYNCRETOCARPUS Blake. 
The most distinct of these genera is unquestionably Syncreto- 
carpus, whose corky-margined fruit is something of an anomaly in 
the Viguiera group, nor is it quite the same as that of the Verbesina 
series, the genus being indeed in some degree a link between the 
two groups, but presumably more nearly related genetically to 
Viguiera. 
The genera Hymenostephium and Haplocalymma, with the sec- 
tion Diplostichis of Viguiera and four species of the genus hitherto 
treated as Gymnolomia form a group so closely related in all 
features but the technical one of pappus-character that it seems 
impossible to doubt their common origin. In habit, foliage, most 
details of involucre, shape and pubescence of achenes, and the 
technical points of their androecia and gynoecia they are closely 
and often confusingly similar, and with the exception of Haplo- 
calymma, technically distinct enough in its uniseriate 5-leaved 
involucre, offer no differences of more than specific value in any of 
these features. Between H ymenostephium cordatum and some 
forms of Gymnolomia costaricensis, for instance, no one has yet been 
able to discover the slightest difference aside from the presence or 
absence of pappus and, what seems here as elsewhere a character 
in some way linked with this, the concomitant presence or absence 
of hairs on the achene. All occupy portions of the same general 
