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great abundance. The seeds of some annuals when buried in the soil retain 
their vitality for long periods. Mustard seed, for instance, has been known 
to lie in the soil for a quarter of a century and then when placed in a 
favorable environment, grow into vigorous nlints. In this class we have 
such common weeds as dodder, foxtail, smartweed, Russian thistle, crab- 
grass, pigweed, lamb’s quarters, dog fennel, barnyard grass, tickle grass, 
bracted plantain, ragweed, corn cockle. night-flowering catchfly, mustard 
and whitetop. 
ee 
Buckhorn. 
Biennials are those plants which spring from seed and produce only a 
eciuster of leaves the first season. In these leaves are manufactured and 
stored large amounts of plant food for use during the second season of 
growth. During the second season, a flower stalk is sent up and many 
seeds formed, after which the plant dies. This group depends on seed for 
propagation. Here belong wild carrot, wild sweet clover, burdock and com- 
mon evening primrose. 
