river indicate the occurrence there of Hevea microphylla: 
‘The lower part of the Dimiti is mostly very deeply 
flooded igap6 with the low vegetation characteristic of 
such areas... . About 20 kilometers from the mouth up- 
stream, Hevea microphylla appeared. It becomes more 
and more abundant as we go upstream. It is a low tree 
of perhaps some 35 feet with at least 10 feet of this now 
under water insome places... . Further upstream, the 
river is reduced to a mere channel of about five feet in 
width winding very tortuously through deeply flooded 
igap6 with an occasional knob of highland.”’ 
One of the most unusual habitats for Hevea micro- 
phylla is the low, almost treeless open ‘‘caatinga’’ in the 
lower part of the Igarapé da Chuva which empties into 
the Rio Uaupés at Taracud. Here, Hevea microphylla 
occurs, standing alone with an occasional and stunted 
Bombax, Moronobea or Ambelania in an open area—a 
‘‘lake’’ in the season of high water—covered with a very 
dense growth of tall grasses and sedges. The seringueira 
tambaqut in this locality is a small treelet about 20 feet 
tall with a crown of but two or three branches. The basal 
part of the trunk was characteristically swollen. There 
is, indeed, a striking parallel in the size and shape of the 
treelet and in the ecological factors between Hevea mi- 
crophylla in this habitat and HZ. pauciflora var. coriacea 
(HI. minor) at the mouth of the Rio Guainia. [ have 
never seen the tree (Hevea microphylla) as small as “‘ten 
feet,’’ as reported by Baldwin (loc. cit.), but it becomes 
very small. This is due, without a doubt, to the almost 
permanent flooding of the locality and the resulting in- 
terference with normal growth habits. 
COMMON NAMES OF HEVEA MICROPHYLLA 
Hevea microphylla is most widely known as seringue- 
ira tambaqu?. This name is used throughout its range. 
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