194 THE AUSTRALIAN- NA'TURALIST 
POLLEN GRAINS OF FAMILIES EPACRIDACEAR, 
PROTEACEAE AND MYRTACEAE. 
(By Miss Agnes A. Brewster.) 
The pollen grains of the Family Epacridaceae are 
very interesting, owing to the fact that in the genius 
Hpacris the tetrads or four pollen grains (daughter cells) 
have been retained. The four grains of each tetrad are 
fused, to form a solid mass, and on germination there are 
four pollen tribes developed, one from each grain of the 
tetrad. The grains vary slightly in appearance in the dif- 
ferent species. Those of EH. obtusifolia are solid-looking, 
with a roughened surface, and the tetrad structure can be 
seen with difficulty. The genera Woollsia, Sprengelia, 
Richea, also have tetrads. Kerner and Oliver quote Leuco- 
pogon as having tetrads, and this may be the case with 
the specimens they examined. Single grains were obtained 
in Lb. virgatus, L.  ericoides, L. lanceolatus, LL. 
amplexicaulus. It will be necessary to test L. Richei, for 
this species grows around the shores of Botany Bay. where 
the material was probably collected by the early botanists, 
who sent their specimens home to Europe to be identified. 
Astroloma pinifolium is an interesting type, whose 
pollen grains seem to be in a transitory stage between the 
tetrads and single grains—there were trios and couples and 
single grains, as well as tetrads. 
The pollen grains of Proteacew are very typical of 
the order. The grains have usually a distinct triangular 
form, more or less bulged, to look like little pincushions. 
At each of the three angles are distinct caps of thin walled 
tissue, forming ‘‘corner-caps,’’ for the exit of the pollen 
tube from one of these. The corner-caps are small in 
Lambertia, and the grain is very regular, with straight 
edges. This is the case also with those of the Waratah, but 
in the latter the caps are rounded, yet small. The grains 
of Hakea and Grevillea are very similar and very charac- 
teristic, with very much enlarged corner-caps, and bulged- 
looking sides of the triangle. Conospermum has grains with 
distinct corner-caps, which have vertical striations, These 
