The Roanoke times. [volume] (Roanoke, Va.) 1890-1895, 1891-09-25
SPREADING SEEDS.
natures Methods of Securing Fertile Seed
I'm Gno1 Soil

Natures Methods of Securing Fertile Seeds
In Good Soil.
The methods by which seeds are dis
tributcd are most curious and interest
ing, says knowledge. The lcgume of
the pea splits along its two margins,
the two halves falling away from each
other and throwing off the seeds in
various directions. The seed cases of
the pansy and the violet explode, scat
tering the seeds forcibly.
In the gorse and the broom n sudden
burst of the pods and spring-lillc twist
of their two halves cfrcctually dispense
the contents. On sunny July days the
cracking sounds produced by the burst
ing pericarps may be distinctly heard.
The mature fruit of Ecballium clatcr-
1um separates from its stock and elects
ITS seeds with great rapidity through
the orificc left by tho rupture. The
sporangia of many ferns (bracl1en) have
an elastic ring, which is probably in
tended for the energetic dispersal of the
spores. In certain pines the scales of
the cone, when thoroughly dried by the
hot days of the summer following that
OF its production, open with jerk,
forcibly ejccting the winged seeds.
Frequently IL number will burst to-
gether, and then the sound may be
heard at great distance.
In the expulsion of the seeds of the
balsam Cmpatiens) the contact of some
outside object is of advantage. The
seed case consists of one cell with five
valves and, if touched by accident
when rIPc, it ut once bursts open, the
valves coilinS themselves violently, and
sprlnging from the stalk, scatter the
seeds III all directions. In the poppy
and snapdragon Il still larger share of
the work of releasing the seeds falls to
an outer agency, for here the pericarp
consists of Il capsule which opens along
the top by valves that leave small pores
through which the seeds fall out when
the capsules are shaken by the wind.
In all of these various methods Of the
expulsion OF seeds il would seem that
they arc due to mechanical causes, and
depend in most instances (impaticns cX-
ceptcD upon Il certain condition of dry
ness i'll themselves, and upon the state
of the surrounding atmosphere.
Passing from the modes in which dry
fruits, consisting of number of seeds
envcloped in tough pcricarps, effect dis
the means which obtain among dry
fruits whose seeds are not collectively
Enclosed i'll Il strong seed case. Here,
too, we find the forciblc election of
seeds. Those of the oat are scattered
with such energy that on fine, dry day
the swapping thus caused is distinctly
audible.
But tho most curious provision pos
scssed by seeds of this class for self
dissemination is the Microscopic avn.
In the wild oat (avcua fatna), for ex-
ample, there are attached to tho
glumclia (a small, lcafy structure con-
ncctcd with the sccd), Il spiral avn COW
cred with humorous fine hairs, and this
avn has the power of expanding when
moist and OF contracting when dry.
Thus the attached seed is constantly
on the move with the changes in the
weather, the hairs clnging to any object
met with, until termination or dcstruc-
ton puts an end to its motion.
The seed of barley, too, is provided
with a similar avn, which is furnished
with minute teeth that point toward it's
apex. The seed, when lying on the
ground, naturally expands with the
moisture Of the night and contracts
with the dryncss of the day, but, as the
teeth prevent its moving toward the
point of the avn, all motion must be in
the direction of the base of the seed,
which will thus travel many feet from
the parent stalk.