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GRINDELIA SQUARROSA, Dunal. (Plate IV.) 
(Gum Plant ; Rosin Weed.) 
Annual; branching from the base; 1 to 2 feet high. Leaves 
sessile, rigid, spatulate to linear-oblong, narrowed at the base below, 
broadened and half-clasping above, acutely serrate or denticulate. 
Heads of yellow flowers rather large, terminating the branches. 
Involucre strongly squarrose with the spreading and recurving 
short filiform tips of the bracts; very viscid, especially at time of 
flowering. Rays narrow, very numerous. 
This species is very common in all territory west of the Missis¬ 
sippi ; it is extending eastward, and has been reported from Minne¬ 
sota, Iowa, Missouri, and Illinois. Here it is most conspicuous 
along road-sides and on plains that have been broken up and then 
neglected ; it invades cultivated land, and locally is very trouble¬ 
some in corn-fields. The sum of its pestiferous and undesirable 
qualities warrants giving it a place among our worst weeds. 
IVA AXILLARIS, Pursh. (Plates V. and VI.) 
(Poverty Weed.) 
Herbaceous, perennial, from woody creeping root-stocks; 
branching, 6 inches to 1 foot high, equably leafy to the top. Leaves 
sessile, obovate or oblong, tapering to a narrow base, entire, obtuse, 
about 1 inch long, minutely appressed pubescent. The small, 
greenish heads on short recurved pedicels, solitary in the axils of 
the leaves. Common from the Missouri River to the Pacific, and 
from New Mexico to British Columbia. The natural home of the 
plant appears to be in sandy or saline soils, but it adapts itself to 
all soils, and is everywhere very troublesome. Once established on 
the farm or in the garden, it spreads rapidly and is difficult to erad¬ 
icate. Plants produce a moderate quantity of seed, but multiplica¬ 
tion is mainly by the extension of the running root-stocks. Like 
the “ quack grass,” the breaking up of these root-stocks only in¬ 
creases the number of plants; pieces may be transported across a 
field on the tools used, and there take root, thus assisting the distri¬ 
bution. Constant cultivation, and the removal of the root-stocks 
from the soil, is the only remedy. 
IVA XANTHIIFOLIA, Nutt. (Plate VII.) 
Annual; tall and coarse, 3 to 7 feet high; pubescent, at least 
when young; leaves mostly opposite, large, broadly ovate, incisely 
serrate, acuminate, 3-ribbed at base, scabrous above. The small 
heads nearly sessile in crowded, spike-like panicled clusters from the 
axils of the leaves, and terminal. 
