Agriculture Reference
In-Depth Information
Simple perennials
normally reproduce by seeds. However, root pieces
which may be left by cultivation can produce new plants. Examples are: dan-
delions, plantain, trees, and shrubs.
Bulbous perennials
may reproduce by seed, bulblets, or bulbs. Wild
garlic, for example, produces seed and bulblets above ground and bulbs below
ground.
Creeping perennials
produce seeds but also produce rhizomes
(below-ground stems), or stolons (above-ground stems that produce roots).
Examples include johnsongrass, field bindweed, and Bermudagrass.
C.
WEED CLASSIFICATION
1.
Land Plants
Most pest plants on land are grasses, sedges, or broadleaves.
a.
Grasses
Grasses have fibrous root systems. The growing point on seedling
grasses is sheathed and located below the soil surface. Some grass species are
annuals; others are perennials. Grass seedlings have only one leaf as they
emerge from the seed. Their leaves are generally narrow and upright with par-
allel veins.
b. Sedges
Sedges are similar to grasses except that they have triangular stems and
three rows of leaves. They are often listed under grasses on the pesticide label.
Most sedges are found in wet places, but principal pest species are found in
fertile, well-drained soils. Yellow and purple nutsedge are perennial weed spe-
cies which produce rhizomes and tubers.
c.
Broadleaves
Broadleaf seedlings have two leaves as they emerge from the seed. Their
leaves are generally broad with netlike veins. Broadleaves usually have a tap-
root and a relatively coarse root system. All actively growing broadleaf plants
have exposed growing points at the end of each stem and in each leaf axil.
Perennial broadleaf plants may also have growing points on roots and stems
above and below the surface of the soil. Broadleaves contain species with an-
nual, biennial, and perennial life cycles.
