Page 134 - Florida Pest Control Examinations

KEY PARTS OF GRASSES

By: Nancy Schaible

Plant or leaf surfaces without any pubescence (hairs) are often called glabrous

IDENTIFY YOUR WEEDS by Gary King, Ph.D.

One of the first things to do is to identify the problem weeds. You will need to know that weeds are
usefully grouped into 3 categories: Broadleaves, grasses, and sedges. The broadleaved weeds
emerge from the seed with their first 2 cotyledon leaves, which also gives them the name, dicot. Then
they form more mature leaves with characteristically branched or net-like veins. Broadleaves also have
exposed growing point(s) at the top of the plant and growing points in the leaf axils. They develop
either a taproot or a thicker branched root system. As the grasses and sedges emerge from seed, there
is only at first a single cotyledon leaf, giving them the moniker, monocot. These plants’ leaves have
parallel veins that are easily seen on mature plants. Monocots have protected growing points that send
up shoots from below the soil surface. They also tend to have fibrous root systems.

The number of cotyledon leaves gives you the first clue, and the subsequent growth further aids in
identification of the very youngest weeds. With fresh samples of the seedling weeds and the flowers,
fruit, seed, and roots of the mature stages, your local agricultural advisor may use weed photos and
plant keys to determine the names of your weeds and help formulate your weed management plan.
Next, weeds are classified as annuals, biennials, or perennials. Annuals may either be winter/cool
season or summer/warm season types. They survive only one season, but must be stopped from
producing seeds that will germinate the next year. Biennials grow for 2 seasons, producing a rosette
stage one year, followed the next year by the dreaded seed production. Perennial weeds grow over
many years, often producing many of those nasty seeds over the years. Perennials are often the most
persistent and difficult to control, since many also form invasive or resistant structures such as stems
that creep under the soil (rhizomes) or sneak over the soil surface (stolons), as well as tubers or fleshy
roots.

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