HOW PLANTS PROTECT THEMSELVES 349 
417. Plants with Weapons for Defense.! — Multitudes 
of plants, which might otherwise have been subject to the 
attacks of grazing or browsing animals, have acquired 
what have with reason been called weapons. Shrubs and 
trees not infrequently produce sharp-pointed branches, 
familiar in our own crab-apple, wild plum, thorn trees, 
and above all in the honey locust (Fig. 84), whose formida- 
ble thorns often branch in g 
avery complicated man- 
ner. 
Thorns, which are 
really modified leaves, are 
very perfectly exempli- “4 
fied in the barberry (Fig. 
243). It is much com- (°A\ EN ' 
7 
moner to find the leaf (Ay “\A' 
, 2 Aol Gh 4 XY\ Fic. 244.— Leaf of a Night- 
extending its midrib.or \\ ~~ shade (Solanum atropur- 
= 
its veins out into spiny ; pureum). 
points, as the thistle does, or bearing spines or prickles on 
its midrib, as is the case with the nightshade shown in Fig. 
244, and with so many roses. Prickles, which are merely 
hard, sharp-pointed projections from the epidermis, are of 
too common occurrence to need illustration. 
Stipules are not infrequently found occurring as thorns, 
and in our common locust (Fig. 246) the bud, or the very 
young shoot which proceeds from it, is admirably pro- 
tected by the jutting thorn on either side. 
418. Pointed, Barbed, and Stinging Hairs. — Needle- 
pointed hairs are an efficient defensive weapon of many 
plants. Sometimes these hairs are roughened, like those 
1 See Kerner and Oliver’s Natural History of Plants, Vol. I, p. 430. 
