South America by its unusual size. It is a robust plant 
that normally reachesa height of five and a half or six feet. 
This extraordinary plant inhabits the immense sand- 
stone savannahs to the north of the Colombian part of 
the Rio Vaupés above Mitu. It has been collected at 
Yapoboda at the headwaters of the Rio Kuduyari and at 
Kanenda on the Rio Kubiyi. An aeroplane reconnais- 
sance has shown that these two savannahs are continu- 
ous. I have seen this plant, but was unable to collect it, 
on the great savannahs of Goo-ran-hoo-da on the Rio 
Karurti in the upper Vaupés. The Karurti savannahs may 
possibly be continuous with Kanenda and Yapoboda. 
Paepalanthus Moldenkeanus undoubtedly represents 
another of the curious endemic plants which have turned 
up during our investigation of these ancient quartzitic 
savannah formations in the Vaupés. 
Growing in close proximity to Vellozia lithophila, Bom- 
bax coriaceum, Hevea nitida var. toxicodendroides, Leit- 
gebia colombiana and Styrax rigidifolius forma yapoboden- 
sis,’ Paepalanthus Moldenkeanus is admirably adapted to 
the extreme conditions of xerophytism which obtain on 
these savannahs. It occurs in isolated colonies of from ten 
to fifty individuals in slight depressions or swales on the 
usually flat savannah. These swales are moist and highly 
acidic and are repositories of very interesting grasses and 
sedges, as well as xyridaceous, lentibulariaceous and erio- 
caulaceous species. There are a number of other species of 
Paepalanthus in the same localities, but all are diminu- 
tive plants. 
It is appropriate that I dedicate this majestic new 
species to my friend, Dr. Harold N. Moldenke, in recog- 
nition of his extensive researches in the family 2/riocaul- 
acede. 
'Steyermark (in Fieldiana 28 (1953) 492) considers Slyrax yapo- 
bodensis (Idrobo & R. E. Schultes) Steyerm. to be a distinct species. 
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