weeds can be classified into 3 major groups

  • Grasses.
  • Sedges.
  • Broad Leaved Weeds.

Grasses

Grasses have stems or culms that have nodes and internodes. Nodes are the well defined solid swellings at regular intervals on the stem from which leaves arise. The internodes, the portion of the culm between the nodes, are usually hollow. The leaves of grasses, which arise alternately from the nodes with sheath and blade. The sheath is wrapped around the culm. The blades are long, narrow and hare parallel veins.
At the junction of the blade, the sheath is usually a papery membrane called ligule . The unit that consist of the flower, lemma, and palea is the floret. A group of spikelets makes up an inflorescence to which is either panicle, a raceme or a spike. Grasses ex: Echinochloa colona, Eleusine indica.

Important diagnostic parts of grass weeds

ligules, Auricles, Leaf tips, appearance of youngest leaf, stolons and or rhizomes, seeds.

Sedges

The sedges are usually solid and triangular. Sedges have three ranked leaves. Each new leaf arises one third of the way around the stem from the one below. The basal portion of each leaf is fused to form a tube around the stem. There is no distinct sheath blade division. The flowers of sedges are not enclosed by a pair of bracts, but usually occur in the axil of a single bract. Ex: Cyperus iria, Cyperus rotundus

Broad leaved weeds

Broad leaved weeds: The group can be distinguished from the grasses and sedges by the presence of expanded leaf blades. The vexation of the leaves may be parallel as in monocots or netted as in dicots. Ex: Commelina benghalensis, Amaranthus spinosus.

Important diagnostic parts of Broad Leaved Weeds

leaf margins, leaf arrangement, leaf attachment, leaf shape, leaf types, stem properties, flower arrangement, specialized parts.
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