Studies in Fitchia — Carlquist and Grant 
F. rapensis. The new taxa clearly belong to the 
second group. The present study also emphasizes 
the distinctness of the third group and the close 
relationship between the two species it contains. 
Fitchia cuneata ssp. tahaaensis agrees with 
typical F. cuneata in most respects. Those by 
which it differs include: presence of sclerified 
tyloses in wood (not yet observed in wood of 
typical F. cuneata ) ; leaves with wider and longer 
laminae; secretory cavities present in leaf meso- 
phyll; involucral bracts thicker; sclerified tri- 
chomes on corolla-lobe tips longer and fewer; 
anther tips longer. These differences are rela- 
tively minor. Close identity of the two sub- 
species is revealed by such critical features as 
general leaf shape, pith structure, bract anatomy, 
corolla vascularization, awn shape and anatomy, 
and pollen size and ornamentation. The two 
taxa are therefore best regarded as subspecifically 
different. This situation is precisely what one 
would expect on account of the closeness of 
Tahaa to Raiatea, sister-islands (within a com- 
mon fringing reef). 
The nearest island to the sister-islands of 
Raiatea is Bora Bora. Qne might expect, there- 
fore, a similarity between F. cuneata and F. 
cordata. These two do appear similar in their 
small heads, relative lack of sclerenchyma in 
involucral bracts, venation and size of corollas, 
lack of secretory cavities in leaves (excepting 
ssp. tahaaensis ) and blunt shape of spines on 
pollen grains. They are dissimilar in that F. 
cordata possesses secretory canals and thin- walled 
nonlignified cells in the pith, has cordate leaves, 
and some sclerenchyma along veins of leaves. 
These characteristics are reminiscent of F. nu- 
tans. From F. nutans , however, F. cordata differs 
by such respects as those in which it resembles 
F. cuneata. Features of F. cordata which do not 
match those of any species in the F. nutans-F. 
cuneata-F. tahitensis group include the presence 
of nonlignified cells in pith, the small leaf size 
and cordate shape combined with relatively long 
petiole length, the presence of both long mul- 
tiseriate sclerified trichomes and sclerified epi- 
dermal cells on corolla-lobe tips, long stamen 
tips, small pollen size, and blunt spines on 
pollen grains. These characteristics, combined 
with the distinction furnished by its geographi- 
cal isolation on Bora Bora, mark F. cordata as 
worthy of recognition as a new species. 
29 7 
PHYLOGENETIC CONSIDERATIONS: The new 
taxa described here, although they contribute 
no anomalous features to the genus, do enlarge 
our picture of it and permit more detailed ob- 
servations in this regard. The monograph of the 
genus provided some notions on the relation- 
ships of Fitchia. These ideas do not seem to 
require alteration. The new taxa do enhance the 
diversity of the Society Islands Fitchias. Indeed, 
Papy ( 1955 ) notes that the Society Islands form 
a center of diversity for Fitchia, and that the 
variability of Fitchia on Tahiti is suggestive of 
this. The latter phenomenon remains a problem 
worthy of study when more material from Tahiti 
becomes available. 
Postulation of phylogenetic trends within 
each species group seems inadvisable, both 
because of the limited quantity of material 
known and the fact that the species seem to 
be variations on a basic theme rather than stages 
along a phylogenetic pathway. However, some 
interpretations of relationship among the species 
groups may be offered here. 
The larger size — in all parts of the plant — 
of F. speciosa, as compared with the remaining 
species, seems specialized. The larger pollen size 
suggests the possibility of a greater chromosome 
number, and the morphology of the awn base 
seems clearly a specialized feature. The fact that 
F. speciosa has such an isolated geographical 
position, the westernmost species of Fitchia, in 
contrast with the likelihood of an American 
ancestry of this helianthoid (e.g., Brown, 1935; 
Papy, 1955), reinforces this supposition. The 
extremely large seeds of F. speciosa seem less 
adapted to long-distance dispersal than the 
smaller seeds of the Society Islands species. The 
most likely interpretation, seemingly, is that 
seed size, and the peculiar adnation of achene 
summit to awn base in F. speciosa are charac- 
teristics acquired subsequent to arrival of its 
ancestors in Rarotonga. Fitchia speciosa may be 
regarded as a highly distinct derivative of the 
Society Islands stock. Although corollas of F. 
speciosa are the largest in the genus, their vena- 
tion is like that of the Society Islands species, 
not that of F. rapensis and F. man gar even sis, 
which have complex corolla venation. 
If pollen-grain size is an indication of chro- 
mosome number, then one would expect the 
Society Islands species to have the lowest num- 
