4 THE AMERICAN MIDLAND NATURALIST 
ledon (Figs. 1 and 2.) (All drawings of the seedling are natural 
size.) The cotyledon itself remains inside the seed to act as an 
organ of absorption. The primary root now strikes downward 
into the soil and may attain a length of about five centimeters. 
the first summer (Figs. 2 to 7.) Meanwhile the hypocotyl gradually 
increases in diameter, and a slit opens in its side through which 
the epicotyl or plumule first appears as a small conical bud (figs. 2 
and 3). The epicotyl pushes out through this slit and grows to a 
length of about one centimeter during the first season, bearing 
usually two or three membranous leaf scales, and at its base one or 
two secondary roots (Figs. 4 to 7). In none of the many seedlings 
observed did the epicotyl produce a green leaf the first year, 
but in all cases the plant remained entirely underground 
until the second spring. It will be seen therefore’ that the 
plant, having no green leaves, can produce no new organic 
material but is dependant until the second summer on that stored 
in the seed. Such of this food material, however, as is not used 
in the first season’s growth does not apparently remain in the 
seed, but is passed downward through the cotyledon and its petiole 
into the hypocotyl, where it is stored in a form probably far more 
readily available than the horny endosperm of the seed. ‘This 
transfer is shown by the fact that before fall the seed and coty- 
ledon are withered and soon afterwards decay, while at the same 
time the hypocotyl becomes enlarged, forming a tuberous body 
about the same in size as the original seed (Figs. 4 to 7). All, there- | 
fore, that the plant does during its first growing season is develop 
a root system, form a good-sized bud (the epicotyl), and transfer 
the remaining food from the seed into the hypocotyl where it will 
be ready for immediate use at the beginning of the second season. 
It will be seen that in this way the hypocotyl as well as the epicotyl 
takes part in forming the embryonic rhizome of the plant. 
By the second spring the decay of the seed and cotyledon 
is complete, and the primary root now also withers away leaving 
thus two scars on the tuberous hypocotyl where these parts 
\ were once attached (Figs. 8 andg). A single long-petioled green 
leaf is now sent up from the tip of the epicotyl; it will be noted 
that this is the first part which is visible above ground, the 
plant being in its second year of growth (Figs. 8, 9). During this 
second summer the old secondary roots also increase in size and 
new ones are sent out from various points on the epicotyl (fig. 9). 
