Sept. 15, 1925 
Reaction of Grasses to Chinch-Bug Attack 
577 
the plants in which tie chinch hugs oveiwinter in their normal 
habitat. On the other hand, glasses not native to Kansas were 
usually found to he severely injured, although in many cases they 
possess plant characters which were commonly found associated 
with resistance in indigenous species. Different species of the same 
genus, which vary primarily only in their natural range, also showed 
marked differences in their reaction to chinch bugs. Therefore, in 
this study the terms “native or introduced” are not used in the 
usual sense, but refer only to whether the species is native to Kansas 
or not. 
CHARACTER OF TISSUES 
A wide difference was noted in the character of the plant tissues of 
different species. In general, however, the plants could be grouped 
into three classes: (1) Those having noticeably harsh, tough, or 
leathery tissues; (2) those with soft or tender tissues; and (3) those 
with tissues intermediate between the two extremes. In Table I 
these characters are indicated in the column headed “character of 
tissues” as harsh, tender, and intermediate. Grasses with harsh 
tissues are harsh to the touch, are glabrous or only slightly pubescent, 
and usually are rigidly erect as to leaf and culm characters. Harsh¬ 
ness in the grasses has been ascribed by some writers to a high per¬ 
centage of silicon in the vegetative parts. Tender-tissued plants are 
pubescent, as a rule, though not always so. The leaves are often thin 
and soft to the touch and are commonly drooping, thus giving a 
somewhat flaccid appearance to the plants. This is particularly 
true of the annual species of Bromus. The third group possesses 
tissues intermediate in character. Plants of this group may be pu¬ 
bescent or glabrous, but the tissues are leathery rather than harsh 
or tender. 
It is interesting to note that such species as Sporobolus cryptandrus , 
S . asper, Sorghastrum nutans , Eragrostis trichoaes , Elymus vvrginicus , 
E. canadensis , Triodia flava, Bouteloua oligostachya y B. curtipendula, 
and Andropogon scoparius , which exhibited the greatest resistance to 
chinch-bug attack, are all perennial native species with harsh tissues. 
These are also the commonest roadside, pasture, and prairie grasses 
in the vicinity of Manhattan. 
TIME OF MATURITY 
The time of maturity refers to the period during which each species 
has been observed to flower and mature seed at Manhattan. In a 
number of cases, however, where new species were being grown for 
the first time and no first-hand information on this point was avail¬ 
able, it was obtained from published floras. A few of the species 
matured before the chinch-bug attack, but the majority would not 
have matured until afterward. Plants of related species in various 
stages of growth were available for observation. In a few cases, 
plants of the same species of various ages were available. Hystrix 
hystrix was a case in point. The plants in row 35 were large robust 
plants, two years old, while those in row 73 were young plants grown 
from the seed in the spring of 1924. In this instance the older 
plants were attacked and killed by the bugs as readily as the young 
plants. In fact, no relation was noted between the stage of maturity 
of the plants and their reaction to chinch bugs. It is, however, 
