41 o The Ohio Naturalist. [Vol. Ill, No. 6, 



OHIO PLANTS WITH CONTRACTILE ROOTS. 



John H. Schaffner. 



One of the interesting phenomena to be observed in stndying 

 geophilous plants is the habit which some have of keeping certain 

 parts of their bod}- below the surface by means of contractile roots. 

 This subject has received the attention of DeVries, Rimbach and 

 others, whose papers should be consulted for a more complete 

 presentation of the subject. 



The burrowing habit may be of advantage in several ways. 

 Many seedlings possess contractile roots, by means of which they 

 reach a suitable depth of soil. In certain plants which produce 

 stolons or runners, root contraction is also an important factor. 

 When the stem touches the ground it strikes root and is soon 

 pulled beneath the surface. 



Rhizomes may develop horizontally, at right angles to the 

 direction of gravity, without being influenced in a mechanical 

 way. There are, however, many, like the long rhizomes of /n's 

 versicolor, which are continuall}'^ growing upward, but contractile 

 roots developed on the under side continue to pull them down 

 into a horizontal position. In such forms as Trillin ni grandiflo- 

 ruDi the short rhizome is not only kept horizontal, but is buried 

 deep in the earth by the strong contraction of the numerous long 

 roots growing out of the under side. 



There are rhizomes and bulbs which develop vertically, and 

 would thus grow out of the ground. But as the stem elongates 

 or dies away below, the newer part is pulled backward by a whorl 

 of contractile roots which grow out on the young nodes near the 

 upper end. Ver}' striking examples of this type are Botryiiiiinii 

 obliquitiu and Spathyona foctida . 



In some plants there is a main tap-root w^hich continues to 

 contract for a long time, and thus keeps the growing points 

 at or near the surface. This may occur in acaulescent herbs 

 or in crownformers like Aquilcgia canadensis and Tacnidia 

 integerrima . 



The following plants have prominent root contraction : 



Botrychiuni obliqiunn. Trillium iinrlulatuin. 



Botrychiuiii dissectum. Hypoxis hirsuta. 



Arisaema tripliylluin. Iris versicolor. 



Arisaema dracontium. Iris hexagona. 



Spathyeina foetida. Allionia nyctaginea. 



Zygadenus elegans. Aquilegia canadensis. 



V'eratrum woodii. Aquilegia vulgaris. 



Hemerocallis fulva. Genliana andrewsii. 



Trillium sessile. Plantago major. 



Trillium recurvatum. Taenidia integerrima. 



Trillium nivale. I.acinaria squarrosa. 



Trillium grandiflorum. Mesadenia luberosa. 



Trillium erectum. Taraxacum taraxacum. 



Trillium cernuum. Taraxacum erythrospermum. 



