48 RENNERT: SEEDS AND SEEDLINGS OF ARISAEMA 
The functional plumules of A. Dracontium exhibit a tendency 
toward degeneration. A comparison of the plumules of the two 
species will well demonstrate the particular instances. The fully 
grown leaves of A. wiphyllum are ovate, the largest being 36 mm. 
in length and 30 mm. in width, while the smaller are 25 mm. 
by 13 mm. The functional leaves of A. Dracontium vary greatly 
meee 
in the shape and size of the lamina and in the length of the petiole. i 
In outline they range from broadly elliptical to nearly circular and 
all bear a mucronate point at the tip as does A. triphyllum. The 
largest leaves of A. Dracontium are about 25 mm. in length by 22 
mm. in width, but the greater number are smaller, some being 
only 6 mm. by 3 mm. The margin of nearly all leaves of A. a7 
phyllum are very finely serrulate ; while some leaves of A. Dracon- 
tium display a tendency to serrulation, more often they are entire. 
The upper surface of the A. triphyllum leaf is covered with faint 
whitish lines ; this appearance is due to the presence of elongated 
raphide cells in the mesophyll directly beneath the epidermis. A. 
Dracontium has numerous raphide cells in the mesophy]l but they — } 
are not so large as those of A. ¢riphyllum and cannot be distin- 
guished without the aid of the microscope. The under surface of | 
the leaves of A. ¢riphyllum is covered with a waxy bloom and the 
- upper surface also shows some wax. In A. Dracontium the wax is 
very much thinner on the under surface and barely discernible 01 j 
the upper. As a consequence the leaf of 4. Dracontium wilts very 
quickly after being removed from the plant. The development of 
stomata on both leaves is about the same. The leaves of both 
species are pinnately net-veined. In A. ¢riphyllum one pair of the 
lateral branches is more strongly marked than the others, fore 
shadowing distinctly the plan of the mature trifoliolate leaf. In A. 
Dracontium the plan of venation is more generalized. The lateral 
veins have all equal value and are neither so well marked as some 
nor so faint as other lateral veins of the leaf of A. triphyl/um. 
The mesophyll of the A. Dracontium \eaf is not so well developed 
nor so well supplied with chlorophyll as is that of 4. triphyllum. 
Those plumules of A. Dyracontium which become assimilatory 
organs are functional for a shorter period than those of 4. diphyl- | : 
‘um, for they wither upon the plant much sooner. Those of long- 
est duration last not more than three months while some send uP 
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