HABIT OF GROWTH OF WEEDS 579 



the underground stems buds arise in the axils of small scaly 

 leaves, and break their way upwards through the soil, ultimately 

 producing stems with leaves and flowers upon them. Each node 

 with its bud and roots may become a separate plant when the 

 intervening pieces of stem are cut or decay. 



4. Habit of Growth of Weeds. — Weeds display considerable 

 variety in their manner of growth, and careful observation of 

 their peculiarities in this respect is of great importance, as these 

 points must be taken into account in devising effective methods 

 of extermination. 



A large number have straight stems which rise up vertically 

 from the ground and may be termed erect weeds. They usually 

 have few leaves near the surface of the ground and many of them 

 are annuals. 



Another series are met with whose stems are too weak to stand 

 upright, and consequently trail along the ground, at the same 

 time branching out in all directions and covering up large areas 

 of the surface with their leaves. Their root-system is well 

 defined, and their stems do not take root at the nodes but 

 merely lie fla on the ground. Such are spoken of as prostrate 

 weeds. Very good examples are seen in chickweed, field madder, 

 knotgrass and broad-leaved toad-flax. These, like the erect 

 weeds, are generally annuals, and are readily destroyed by pre- 

 vention of seeding and use of tillage implements. 



Nearly allied to these so far as concerns their habit of cover- 

 ing the ground with stems and leaves are creeping weeds,, and 

 weeds with short contracted stems ; the former have stolons or 

 runners which take root at their tips or nodes, and the latter 

 short stems with rosettes of leaves spread out on the surface of 

 the ground. Typical examples of creeping weeds are creeping 

 crowfoot and silver-weed, while the broad-leaved plantain, daisy 

 and dandelion are representative of weeds with contracted stems. 

 These are mostly biennials or perennials, and occasion much 

 trouble to eradicate when well established. 



