roots to tops by weight ranges from about 0.8:1 to 1.5:1 for most 
native grasses. 
Soil factors influencing root growth are moisture, tempera- 
ture, structure, depth, fertility, and chemical reaction. Soil mois- 
ture, generally, has the greatest effect on root depth. In shallow 
soils, root systems are shallow; in moist, deep, well-developed 
soils, root systems are deep. Grasses differ widely in their ability 
to grow in saturated, poorly aerated soil. Excessive wetness in- 
hibits root growth of most grasses except those adapted to 
marshes. 
Soil temperature affects the growth of grass roots. In general, 
native perennial grasses have active root growth in the fall until 
frost, very slow growth through winter, and active growth again 
in spring from about 10 to 15 days before green leaves appear 
until flowering. After flowering, growth slows down and stops 
during summer when soil temperatures are high. 
The amount and frequency of top-growth removal by grazing 
or mowing have a marked influence on root growth. According to 
research (Crider, 1955), the proportion of roots that stop grow- 
ing varies according to the proportion of top growth that is re- 
moved. 
Stems 
The jointed stem (culm) of a grass plant consists of nodes and 
internodes. The nodes (joints) are solid and usually larger than 
the rest of the stem. The internodes, the part of the stem between 
two nodes, are usually hollow. 
Branching at the base of the main stem may produce erect 
shoots; horizontal, above-ground stolons (stoloniferous) ; or hori- 
zontal, below-ground rhizomes (rhizomatous). Both rhizomes and 
stolons bear roots at the underside of the nodes. 
Some species of grasses branch only at or near the base from 
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