soft and juicy,
considerably like a ripe tomato.

30. Shot off by wind or animal.--The calyx of sage, bergamot, and
most other mints, remains dry and stiff, as a cup to hold one to four
little round nutlets as they ripen. The figure shows two of these
in section, as they are attached to the main stem of the plant, or
one of its branches. Observe the direction taken by the upper and
by the lower points of the calyx. When dry, the plant behaves somewhat
as follows: when the wind jostles the branches against each other,
or when an animal of some kind hits the plant, this movement causes
many of these cups to get caught; but the elastic stem comes suddenly
back to its place, and in so doing flips a nutlet or more from its
mouth one to six feet, somewhat as a boy would flip a pea with a
pea-shooter. In our garden, July 2, when plants of sage, _Salvia
interrupta_, were ripening their fruit, we found it difficult to
collect any seeds, but seedlings were observed in abundance on every
side of the plant, some to the distance of six feet. Plants dispersing
seeds in this manner have been called catapult fruits. Examine
ripening fruits of blue curls, pennyroyal, germander, balm,
horehound, dittany, hyssop, basil, marjoram, thyme, savory, catmint,
skullcap, self-heal, dragon's head, motherwort, and various dry
fruits of several chickweeds.

[Illustration: FIG. 39.--Ripe calyx of sage, first as pushed down;
second as let loose throwing nutlets.]

31. Seed-like fruits moved about by twisting awns.--Most of the
grains of grasses are invested with glumes, or chaff, and a
considerable per cent of the chaff has awns, some of which are well
developed and some poorly developed. The distribution of such grasses
depends on several agents--wind, water, and animals. The chaff and
awns of all are hygroscopic; that is, are changed by differences
caused by variation of moisture in the air. Sweet vernal grass, tall
oat grass, holy grass, redtop, animated or wild oats, blue-joint,
and porcupine grass are among them. When mature, the grain and glumes
drop off, or are pushed off, and go to the ground. When moist, these
awns untwist and straighten out, but when dry they coil up again;
with each change they seem to crawl about on the ground and work down
to low places or get into all sorts of cracks and crevices, where
the first rain is likely to cover them more or less with earth, after
which they are ready for growth.

32. Grains that bore into