114 Rhodora |JuLY 
shorter than the others. In one variety, the spores are trilobate in 
outline; in all, they are vernicose-reticulate with low, flat-topped 
ridges. 
The farinose indument of the lower surface of the lamina is secreted 
by minute glands, well described and figured by Blasdale, Erythrea, 
i. 253, pl. 2. When they occur on the leaf-surface, these glands are 
borne on short unicellular stalks, as figured by him: when, however, 
they grow along the veins, among the sporangia, the stalks lengthen, 
becoming two or three cells long and raising the secreting terminal 
cells above the sporangia. In addition, many specimens of P. tri- 
angularis bear on the under surface of the lamina long-stalked glands 
with shining, wine-colored, pyriform heads nearly twice as large as 
those of the indument-secreting glands. What their function may 
be is not apparent. When glands occur on the upper surface, they 
are similar in size and structure to the secreting glands of the lower 
surface. They produce either a somewhat farinose or an apparently 
gumm y substance, but only in small quantities. 
Occasionally, as noted by D. C. Eaton, Contr. Nat. Herb. iv. 227, 
the glands of the lower surface fail to function (perhaps, as he sug- 
gested, because of an excess of moisture or shade), producing little 
or none of the usual farinose indument. They then appear as distinct 
but numerous, yellow dots and these, seen against the green of the 
leaf-tissue, probably give the appearance which has led to such 
specimens being distributed as * bronze-powdered forms." A merely 
glandular appearance of the lower surface must, however, be taken 
with some caution in the case of old herbarium specimens which may 
have been poisoned with corrosive sublimate. "The alcohol in this 
compound, if applied in sufficient quantity, entirely removes the 
soluble indument. A good example of its effect is seen in the National 
Herbarium specimen of Palmer's no. 856 in 1889 from Guadelupe 
Island, Lower California. In this plant, the under surface appears 
merely glandular except for the tips of the pinnae which escaped the 
corrosive sublimate bath or brush and are thickly covered with white 
indument. With a little practice, one learns to distinguish poisoned 
specimens by a certain drenched and matted appearance under a lens. 
Maxon, Contr. Nat. Herb. xvii. 173 (1913), has shown that the 
correct generic name for the group here considered is Pityrogramma 
Link, Handb. Gewachs. iii, 19 (1833). 
