496 
STRUCTURE AND LIFE HISTORIES 
No species of palm has ever been found in both the 
eastern and western hemisphere, except when introduced 
artificially. Many of the palms have great commercial 
value, such as the date palm, cocoanut palm (Fig. 383), 
fan palm, vegetable-ivory palm (whose endosperm is 
hard and white like ivory), and the oil palm. In the trop- 
ics the leaves of various species are used to make thatched 
FIG. 380. Johnson-grass (Sorghum halpense). Spikelets in a panicle. 
(After Britton and Brown.) 
roofs, and the trunks are often used for fence posts and 
porch pillars. 
431. Arum Family (Araceae). The arum family is 
well illustrated by the "skunk cabbage" (Symplocarpus 
fcetidus) (Figs. 384 and 385). 1 The flower has no petals, 
but four sepals, and four stamens one opposite each 
sepal. The ovary contains only one suspended ovule. 
The compound globular fruit is composed of the spongy 
spadix, greatly enlarged, bearing the coalesced ovaries, 
with the spherical seeds just underneath the surface. 
1 Called by some authors, Spalhyema ftsiida. 
