alabastro 5-6 mm. in diametro. Sepala quinque, aurea, 
in maturitate sicca atque persistentia, obovata vel subro- 
tundata, 6-7 mm. lata, plusminusve 9 mm. longa, extus 
dense aureo-setoso-secabrida, inter setis minutissime et 
densissime albido-subcrystallino-squammata, margine 
minutissime ciliata, intus glaberrima. Petala quinque, 
alba, fere usque ad basim libera, membranacea, glabra, 
subquadrangulate rotundato-ovata, margine undulata, 
plusminusve 7 mm. lata, 7 mm. longa. Stamina plus- 
minusve quadraginta, corollae basi valde adhaerentia, 
basi longe et dense lanato-barbata. Staminum filamenta 
2.5-8 mm. longa; antherae flavae, versatiles, 8 mm. lon- 
gae. Ovarium globosum, quinque-partitum, glabrum, 
2.5 mm. in diametro, quinque cum stylis carnosis parvis- 
que. Fructus adhuc ignotus. 
Saurauia Alvaroi may be distinguished from all other 
known concepts of the genus by a most curious canal- 
like pouch which is formed by two conspicuous vexilli- 
form flaps arising perpendicularly from the base of the 
leaf blade along the midrib and which are joined together 
at their apical and basal ends. The purpose of this un- 
usual structure is not clear. In none of the many leaves 
examined on the type tree and others was there evidence 
that the flaps might in any way be concerned with insect 
habitation. In all examples, the canal was empty. This 
species, which I can relate closely to no known concept, 
likewise differs from most Colombian species of Saurauia 
in its large number of stamens and in having an almost 
entirely glabrous upper surface of the leaves. 
The exceptionally rich cloud forest which clothes the 
Portachuelo or Sachamates range between the Valley of 
Sibundoy and the great Amazonian planada beginning 
east of Mocoa constitutes one of the botanically most 
virgin areas of Colombia. The genus Saurauia is rela- 
tively well represented in the parts of this forest lying 
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