412 BOTANICAL GAZETTE [JUNE 
, 
one-sided pull, the bulb-axis into an oblique position. In half | 
grown specimens the roots acquire their greatest diameter, 7 
about 6™", and probably also the greatest amount of shortening, | 
and drag the bulb every year 1 to 2™ downwards ( fig. 4). Their | 
course is very characteristic, the contractile basal portion point- 
ing almost vertically downwards, the inactive terminal portion 
passing into the horizontal direction. The central cylinder in : 
these roots is usually 8-archic. In full-grown, old specimens, ’ 
the growing point of which, as a result of the dragging of the : 
roots, lies at a depth of 10 to 12°, the roots are thinner, at most 
3™" in diameter, start equally from all sides of the bulb-axis, 
and run in a flatter course (fig. 5). Their central cylinder has 
on an average nine rays, that of the branches three rays. In 
_ April, when the contraction is ended, the endodermis is furnished 
_ with exceedingly strong 0-thickenings of yellow color, the hol- 
low of the cells sometimes almost being filled up; but thin- 
: walled passage-cells are present in front of the hadrome-rays. 
_ The cortex is copious. Root hairs are numerous. The bulb 
: eps, as a rule, a vertical position, elongates from 3 to57 
: — year, and comprises the products of two years. © : 
_ Remarkable are the differences between the contractile basal 
Portion and non-contractile terminal portion of the root. For e 
in tance, the central cylinder preserves its diameter through- . 
ut its whole length, only the number of rays diminishing very — 
ard the tip; the cortex, on the contrary, is twice as 
the basal region as in the terminal. Furthermore, t the y 
L ial-longitudinal walls of the endodermis acquire, in conse — 
uence of the shortening, a strong undulation in the basal part - : 
the root (fig. $), whereas in the terminal part they do not — 
ow this peculiarity (fig.7). Finally, the endodermis remains — 
1 the basal region thin-walled, until the contraction is finished, 3 
hile in the non-contractile terminal region the —— 
> their ciomomaae before that time. 
ROGALUM -PoMERIDIANUM Kunth. 
pomeridianum grows in dry, open local ie 
— Inits manner of life it shows much r 
