ILLECEBRACEAE (KNOTWORT FAMILY) 133 
and whitened under-surface specked with minute black dots. 
Flowers very small, scarcely a twelfth of an inch broad, in 
clusters of two to six on very slender peduncles; calyx, funnel- 
shaped, five-ribbed and five-lobed, white or purple ; stamens five or 
fewer, exserted. The single seed is about an eighth of an inch 
long, shaped like a reversed pyramid, the sides strongly five- 
ridged, the top flat. When in the soil the seed retains its vitality 
for several years. (Fig. 85.) 
Means of control 
In cultivated ground, very thorough and continued tillage in 
order to prevent the distribution of late-maturing seeds. In 
meadows the hay should be harvested while the weed is in its first 
bloom, with repeated cuttings as the plants recover. But rankly 
infested fields require to be put under cultivation, which should be 
followed by heavy seeding with clover. 
KNAWEL 
Sclerdnthus dnnuus, L. 
Other English name: German Knot-grass. 
Introduced. Annual and winter annual. 
Propagates by seeds. ; 
Time of bloom: March to October. 
Seed-time: May to November. 
Range: Eastern United States and Canada, 
from Quebee and Ontario to Florida. 
Locally as far inland as Ohio. 
Habitat: Gardens, lawns, fields, meadows, 
and roadsides. 
An inconspicuous but persistent little weed, 
as its season of bloom and fruit is both early 
and late and the seeds when undisturbed in 
the soil retain their vitality for several years. 
Roots tough and fibrous, sending up a 
number of slender, light green, fork-branched 
stems, three to six inches long, usually rough- 
: i Fig, 86. — Knawel 
hairy but sometimes smooth, some erect and g¢ieranthus annuus). 
some prostrate and spreading on all sides. x4. 
