290 
PACIFIC SCIENCE, Vol. XVII, July 1963 
semble the figures given (Carlquist, 1958: 6-7) 
for F. cuneata and F. nutans. 
PITH: Pith anatomy proved important in dis- 
tinguishing species of Fitchia (Carlquist, 
1957). Likewise, the two new taxa possess 
characteristics useful for taxonomic purposes. 
Pith of F. cordata (Fig. 11) consists of both 
thick-walled, lignified, and thin-walled, non- 
lignified, cells. Secretory canals are present; each 
is surrounded by an eccentric zone of fibro- 
sclereids. Although secretory canals surrounded 
by small lignified thick-walled cells occur in F. 
nutans and F. tahitensis, the presence of these 
combined with occurrence of thin-walled non- 
lignified cells in pith is characteristic only of 
F. cordata. Pith of F. cuneata ssp. tahaaensis 
(Fig. 12) lacks secretory canals and consists 
of thin-walled and thick-walled lignified cells. 
The only pith pattern which matches this is 
that described in the monograph for typical F. 
cuneata. 
LEAF: Leaf dimensions are mentioned in the 
taxonomic description above. However, aver- 
ages of dimensions of leaves from a collection 
were used in the monograph, and these may be 
compared with those of the new taxa. Mature 
leaves of the collection of F. cordata (Fig. 15) 
show an average lamina width of 52.5 mm, an 
average lamina length of 53 mm, and a petiole 
length of 49.7 mm. The only Fitchia which re- 
sembles F. cordata both in form and dimensions 
is the extreme population of F. rapensis from 
the summit of Rapa. Leaves of F. cordata have 
longer petioles than that collection, and there 
is certainly no close relationship between F. 
cordata and F. rapensis. Leaves of F. cuneata 
ssp. tahaaensis (Fig. 16) which could be termed 
mature show the following average dimensions: 
lamina width, 48.0 mm; lamina width, 87.5 
mm; petiole length, 26 mm. When compared 
with the chart in the monograph (Carlquist, 
1957: 50) the lamina dimensions fall in the 
vicinity of F . nutans and some collections of 
F. rapensis. The leaves are wider than those of 
F. tahitensis but longer than those of the typical 
F . cuneata. Thus, leaf shape distinguishes both 
F . cordata and F. cuneata ssp. tahaaensis. 
Histological features of leaves of the new 
taxa also distinguish them. Fitchia cordata pos- 
sesses fibers in bundle sheaths of many veins, 
but they are lacking in sheaths of finer veinlets. 
No secretory cavities are present in the meso- 
phyll, although secretory canals occur adaxially 
or abaxially to the veins, or both (Fig. 7). 
Mesophyll is about 10 layers thick. These char- 
acteristics are not matched by any other Fitchia 
collection. Presence of a few fibers would ally 
F. cordata to F. nutans or F. tahitensis, but 
these two species possess secretory cavities. Ab- 
sence of secretory cavities does characterize F. 
speciosa and the typical F. cuneata, but these 
taxa lack sclerenchyma in bundle sheaths. 
Leaves of F. cuneata ssp. tahaaensis (Fig. 9) 
lack sclerenchyma along all but the largest 
veins. In addition to the secretory canals above 
and below veins (Fig. 9, left), secretory cavi- 
ties are present in the mesophyll (Fig. 9, right) . 
The mesophyll is about 10 cells thick. This 
description agrees closely with that of typical 
F. cuneata except for the presence of secretory 
cavities. Although such a difference might con- 
ceivably arise from a difference in maturity of 
a plant, it seems more likely a valid difference, 
for specimens of both subspecies were of flow- 
ering age. 
INVOLUCRE: The heads of F. cordata are 
small, and the involucre of a living specimen 
would probably measure about 2 cm in diam- 
eter — the smallest involucre size in the genus 
except for F. tahitensis and F. cuneata. Involu- 
cral bracts of F. cordata (Fig. 13) have a thick- 
ness comparable to some bracts of F. nutans, but 
differ in their lack of the abundant scleren- 
chyma which characterizes bracts of F. nutans. 
The mature state of the bracts of F. cordata 
illustrated is certain, because they came from 
a head in fruit which was in the process of 
shattering. Occasional lignified thick -walled 
cells may be seen along the inner face of the 
bract and around the larger veins. In presence 
of sclerenchyma and other histological charac- 
teristics, the involucral bracts of F. cordata are 
midway between those of F. nutans and F. cu- 
neata. The receptacular bracts of F. cordata 
(Fig. 14) show similar characteristics. As might 
be expected, lignified thick-walled cells are more 
frequent than in the involucral bracts. 
Fitchia cuneata ssp. tahaaensis also has very 
narrow involucres, like those of the typical F. 
cuneata or F. tahitensis. Histologically, involu- 
