Blake — A Revision of the Genus Viguiera 9 
form a somewhat prickly head, least conspicuous in 7’. fruticosa 
Canby & Rose, which is likewise somewhat abnormal in its shrubby 
habit, entire leaves, and in the great reduction of the awns of the 
pappus. The involucre of Tithonia,too, of broad phyllaries sub- 
equal or distinctly graduated and either uniformly subherbaceous- 
submembranaceous in texture or with indurated ribbed base and 
herbaceous tip, is not precisely matched by any species of Viguiera. 
In all these features except the lobed leaves, however, Tithonia 
finds a close ally in four related species of Gymnolomia — G. scaber-° 
rma (Benth.) Greenm., G. Pittieri Greenm., G. calva (Sch. 
Bip.) Gray, and G. auriculata Brandegee — upon the first and 
third of which Schultz’s genus Mirasolia, upheld by Bentham but 
now long discredited, was founded. These four species are of 
course technically distinguished by the complete absence of pap- 
pus, but in no other feature do they offer a distinction of more than 
specific worth. There is moreover a single species of Tithonia, T. 
brachypappa Robinson, in which different heads of the same plant, 
indeed different flowers of the same head, may possess the pappus 
typical of Tithonia (except for the obsolescence of the awns) or 
lack it entirely as in the genus Gymnolomia. The derivation of this 
group of Gymnolomia, which by Hoffmann in 1890 was included in 
Tithonia, from a recent Tithonioid ancestry seems accordingly very 
well established, and the species should be transferred to that 
genus." Among the groups of Viguiera, Tithonia finds its nearest 
allies in the subgenus Amphilepis and the section Hypargyrea, both 
of which occur in the same region as Tithonia, although of eon- 
siderably more restricted range. Of the two groups, all of which 
are perennial herbs or rarely frutescent, the closely related Viguiera 
‘ TrrHonia auriculata (Brandegee), comb. nov. —Gymnolomia auriculata 
Brandeg . Zoe v. 223 (1905). 
- CALVA Sch. Bip. in Seem. Bot. Herald 305 (1 856-57). — Mirasolia calva 
(Sch. Bip.) B. & H. ex Hemsl. Biol. Centr.-Am. Bot. ii. 168 (1881). Gymnolo- 
mia calva (Sch. Bip.) ip.) Gray ex Hook. & Jackson, I Ind. Pie i. pt. 2. 1076 (1893); 
: reenm Cc. oc. . Hist. xxix. 
T. Pittieri (Greenm.), comb. Pini cag:, teagan Pittieri Greenm. Proc. 
: Ol ag 
SCABERRIMA Benth. in Oerst. Vidensk. Meddel. 1852. 91 (1852). — T. 
ats Sch Bip. & H. Gen. Pl. ii. 368 (1873), as syn. Mi 
th.) B. & H. ex — Biol. Centr.-Am. ye 168 (1881). Gymno- 
Am. Acad. xix. 5 : 
ta pl Dlatylepis Gray, : cad. xix. 5 (1883); Rob. we be: 
secure 102 (1899). erie ie T cos 
XXL. 88 Perimeniopsis perfoliata Ip. ex . 
Tithonia glaberrima Ktze. Rev. Gen. i. 371 (1891), sphalm. 
