Seeds:
Mature seeds are usually not yet present on a plant that bears the flowers necessary for
identification. However, in some genera like Mentzelia and Epilobium seed characters may actually be
used as categories in the key. In such cases seeds may be obtained from more mature individuals or
even from fruits of the pereding year. The various seed Testing Laboratories have developed a technique
whereby they can identify the seeds and small fruits of common weeds when they come in as
contaminate in crop seeds, but, here the actual possibilities are limited of course. Many different kinds
of seed are sold to farmers and homeowners each year. So, most be assured of getting correct of seed, it
is important to be able to identify the seed needed. Also, if a mixure of seed is present, it is important to
be able to determine if weed seed are mixure. Some seeds of these weeds are poisonous to human and
animals. Seeds have different characteristics, some seeds are long, short, flat, round or three cornered
while others are smooth or rough and seed weeds have solid color, two-toned or multi-colored
Seeds vary in different ways, the commonest ones listed below: -
1 – Size: - The coconut has a very large seed, the orchid a very small one.
2 – Hairs: - Some seeds bear hairs such as in Epilobium (fireweed) and Asclepias (milkweed), these
functions in aiding the distribution of these objects by wind.
3 – Wings: - Some seeds as well as some fruit have wings, like those borne by some species of Mentzelia
(stickleaf); these may be used in classification.
4 – Shape: - The typical shape is round or oval, but, seeds may vary widely in this respect.
5 – Color: - Seeds may vary strikingly in color, but, sometimes the difference may be so subtle that it can
be perceived only by trained eyes like those of an expert seed analyst. An example of a conspicuous
color is found in a species of Sophora (coral bean) which has a bright scarlet seed.
6 – Surface markings: - Seeds may have very elaborate and striking designs and surface sculpturings,
these often taking the form of raised or indented tracery.
7 – Hilum and raphe: - The scar where the seed broke away from the fruit (hilum) and
the ridge that appears adjacent to it (raphe) often vary in shape, prominence, position

Biological control definition and theory.
Biological control of weeds.
Consideration of biological control of weeds.
Success story of weeds biological control.
Microbial control of weeds.
Biological and Microbial control of weeds in Egypt.
Biological Control Definition
“The use of parasitoid, predator, pathogen, antagonist, or competitor population to suppress a pest population making it less abundant than it would be in the absence of the biological control agent.