344 IOWA ACADEMY OF SCIENCE Vol. XXV, 1918 



resented liy Andropogon nutans, where the coarse buds arise 

 from the base of the growth of the previous year and develop 

 a bunch grass. Sporoholvs ciispidaUis sends up new shoots at 

 every node^* of the thickened rhizome. 



RHIZOMES. 



The pui^i^ose of rhizomes is to absorb nutrition from soil and 

 air through the roots, and to propagate the plants. The shoots 

 may be aerial or subterranean. According to Kraemer, "roots 

 and rhizomes represent those parts of plants which develop 

 underground, the latter having all of the .characteristics of stems 

 except in their manner of gi'owth."^^ They may be distin- 

 guished from the roots by buds, nodes, internodes and reduced 

 leaves in the form of scales. Rhizomes may be uprigkt, hori- 

 zontal or oblique, depending upon their manner of growth, — 

 determined when stem scars are horizontal. This, bowever, is 

 not always possible to do, in case of the rhizomes of grasses. 

 The rhizome, root-stock, and underground stem are synonymous 

 terms; The rhizome may be slender, each branch, terminating in 

 a single shoot as in Poa compressa, or producing several slender 

 shoots as in Poa pratensis, or it may be scalelike with nodes 

 very close together as in Muhlenhergia racemosa. 



ROOTS. 



The roots of the grasses are usually slender and fibrous. Most 

 of them vary in gross structure only as to the length, thickness, 

 and number of root 'hairs. Thus, the roots are not a determining 

 character. 



CULM. 



The culms of grasses, sometimes called stems, are either 

 erect, decumbent or creeping. In case of the latter they are 

 termed stolons, and root at the nodes. The culms are in most 

 instances cylindrical as in Agrostis alba, but some are flattened, 

 as in Poa compressa. 



The sedges may be distinguished from the grasses by. their 

 three-angled stem and straplike leaves. The grasses have two 

 ranked leaves while the sedges have three. 



"This is true in all instances noted. 



"Kraemer, Henry, Botany and Pharmacognosy, p. 443. 



