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PHILIPPINE URTICACEAE. 509 
essentially, but in such a way as to make it an extremely difficult thing 
to describe in exact terms, and with rare exceptions it is quite unsuited 
to the requirements of a key. It is probable that the final ultimate line 
of separation will be made on the nature of the staminate receptacles. 
These show a gradual increase in complexity, with increasing coalescence, 
but have a definite typical structure, which it is often difficult to follow in 
the more complicated species, but which seems always to be present. 
This is the presence of an outer pair of opposed bracts, each having at 
each margin and interior to them another bract, the latter more often 
infolded and inclosing the flowers: in addition to these 6 outer bracts 
there may be and in the majority of cases are others. As regards the 
peduncles, the evidence of Philippine species is that they furnish good 
characters, but have to be handled with discretion. One type possesses 
very slender peduncles of varying length, but usually comparatively 
long: in other cases some of the receptacles are sessile with others on 
the same plant shortly peduncled. In the latter cases, the explanation 
is often merely that of age, in others the difference is real, but such pe- 
duncles are usually comparatively stout, due no doubt to the fact that 
the plants or at least the receptacles are of large or more than average 
size. The fact that one plant has peduncled staminate receptacles while 
another otherwise alike has sessile pistillate ones, is of no distinctive 
value at all: about half of our species have peduncles to the staminate 
receptacles, while they are found for the pistillate in only a very few 
species. 
The bracts of the receptacles are nearly always more or less keeled, 
rarely almost forming a wing: this keel in a majority of cases becomes 
free at or below the apex of the bract, and the free portion may protrude 
well beyond the apex of the bract itself. This is often a very striking 
character in the field, but is more difficult to use in the herbarium, and 
is open to two qualifications. It is not unusual for the outer bracts to be 
very definitely corniculate, and the inner to show this to a much less 
extent: and the great difficulty is with the species where short spurs are 
present but hardly extend beyond the general outline of the bract. Again, 
it is in the staminate receptacles that this is best shown. The flowers 
seem valueless, except that the pistillate indicate the genus with precision. 
The staminate develop successively, accordingly in even the fewest- 
flowered receptacles, it is often possible to find one on a long pedicel, one 
or two more subsessile and smaller, others minute. ‘he pistillate are 
practically monotypic, except that the achenes often develop striae, but 
these may not be shown by ovaries from the same receptacle. The pres- 
ence of the two kinds of receptacles on the same or different plants is of 
no systematic value: it is possible to look over hundreds of plants of a 
species with only one kind, then to find others with both. Statements 
in the text should be interpreted in this light. Some species of which 
