Studies in Fitcbia—C ARLQUIST and GRANT 
match those of the typical F. cuneata ( Carlquist, 
1957:32). In F. cordata (Fig. 28) the spines 
ate even more markedly blunt. Pollen grains 
of F. cordata (range, 39-51 u; average, 42 fx) 
are the smallest in the genus. The pollen grains 
of F. cuneata spp. tahaaensis (range, 45-51 fi; 
average, 48 /*) closely match those of ssp. cu- 
neata in size. The slightly smaller size of grains 
in the latter may be caused by the fact that 
flowers of F. cuneata ssp. cuneata from which 
grains were taken were not quite mature. Pollen 
grains of F. rapensis (Fig. 30) average 60 u 
in diameter, and have a range from 51 to 66 /x. 
They are thus slightly larger than those of F. 
295 
mangarevensis, although the difference is not 
significant. The spines of pollen grains of F. 
rapensis have an inverted-funnelform shape, like 
those of F. mangarevensis, but appear to be 
more sharply pointed. In addition, lacunae in 
spine tips were observed for the first time in 
the genus in F. rapensis. This feature, however, 
is not unexpected in Fitchia, since other Helian- 
theae have lacunae in spine tips (Carlquist, 
1957:33). 
SPECIES CHARACTERISTICS: In the mono- 
graph three species groups were recognized: 
( 1 ) F. speciosa; (2) F. nutans, F. tahitensis, 
and F. cuneata; and (3) F. mangarevensis and 
Figs. 28-30. Optical sections of equator of pollen grains, showing a third of each grain. Germ pores indi- 
cated at left and right in each. Fig. 28, F. cordata. Fig. 29, F. cuneata ssp. tahaaensis. Fig. 30, F. rapensis. 
