176 BOTANICAL GAZETTE [SEPTEMBER 
to drag the tuber vertically into the ground. I found the grow 
ing point of older specimens mostly in a depth of 3™. 
In Jrillium sessile L. 1 found most of the roots possessing2 
strongly contractile swollen basal portion, which soon becomes 
wrinkled. In this species the tuber very often by the power of 
the roots is drawn into a horizontal or even downwardly directel 
position. 
Mesadenia tuberosa (Nutt.) Britton, a composite growing of 
wet places of the prairie, has a stem-tuber about 2™ in length, 
which yearly grows from 10 to 12™™ vertically upwards, while i 
dies off in the same proportion at its lower end ( fig. ay The tuber 
comprises the products of two years, separated by a constrictiot. 
Every new member of the tuber, in May after its formation, sets 
out about twelve roots, originating in a simple ring. These 1008 
grow obliquely downwards and attain a length of more that 
30™. They are at the beginning about 2™ thick, but ze | 
secondarily in thickness, attaining at least a diametet of (a 
They exhibit considerable contraction, and pull the stem 
much back into the ground as it elongates upwards. The 1008 
seem also to show reserve material. They persist through . 
vegetative periods and form later numerous long but very | 
lateral rootlets, branching sparingly in their turn. ee 
vegetative multiplication by lateral buds, which become ®Y”” 
by the decay of the mother tuber. oe 
The species of Arisaema, Spathyema, Hypoxts, Trill 
Mesadenia mentioned above can therefore be classed togethe 
one group, characterized by possessing a rhizome one 3 
or less vertically upward, which becomes drawn down pF 
tractile adventitious roots. To the same group belong e 
following species: Ayacinthus candicans Baker, Lilium gee: 
L., Allium ursinum 1., Succisa pratensis Moench, 40 
major L. 
ik. ee 
Erythronium albidum Nutt.— During sumine’ ee 
Erythronium albidum \ies hidden in the earth vit ring’ 
ant without roots. I found the growing point of fia 
me tee 
