Native Hawaiian Cotton — Stephens 
387 
Fig. 1. Geographic range of Gossypium tomentosum Nutt, in the Hawaiian Islands (1963). Solid circles 
indicate collection sites; those enclosed in rings represent sites of former collections unchecked during the 
present study. The open circle indicates site of hybrid populations. Shaded areas correspond to regions with an 
average annual rainfall of 20 inches or less. 
range of the species. On Oahu rainfall rises 
rapidly with elevation, and tomentosum was 
not found above an altitude of 100 ft. On Lanai, 
a low island in the rain-shadows of Molokai and 
Maui, scattered populations were found extend- 
ing from sea level to almost 1000 ft. The col- 
lections from Molokai and Maui were obtained 
between 100 and 250 ft. These differences in 
altitudinal ranges agree quite well with the 
vegetation maps published by Ripperton and 
Hosaka (loc. cit. ) . 
ISLAND HABITATS 
1. Oahu 
As shown in Figure 1 , tomentosum is found 
most extensively on the western coastal plain 
in the rain-shadow of the Waianae Range. Here 
it extends in scattered populations from the 
southern extremity of the range, north of Bar- 
ber’s Point, to the outskirts of Nanakuli. North 
of this village is another population around 
Maile Point and extending for about 2 miles 
inland along the Hakimo Valley. Elsewhere 
along the coast only scattered plants were found 
around Kaena Point (from north of Makua 
extending around the point to the north coast ) . 
South of Nanakuli, tomentosum is found almost 
exclusively as an understory, along with Sida 
spp. and occasional Opuntia, in Prosopis (ke- 
awe) scrub. It appears to grow best under par- 
tial shade, i.e., wherever the stands of Prosopis 
are relatively thin. A similar habitat occurs 
around Maile Point, but there a semiprocumbent 
form ( ecotype or plastic variant ? ) has ex- 
tended away from the scrub to the edge of the 
exposed beach. Inland it extends along the Ha- 
kimo Valley as a component of mixed Prosopis 
and Leucaena scrub. On the whole the popula- 
tions are found most commonly on the coastal 
flats, extending a little way up the slopes of the 
Waianae Range, but not ascending to a height 
of more than 100 ft. On the ocean side they 
rarely extend to the strand; the Maile Point 
population is exceptional in this respect. 
