Weed Science, PLS 4601c Section 7644
and Grad. – Prin. Of Weed Science AGR 6932 Section 9212
University of Florida - Davie
Philip Busey, email@example.com
June 3, 2009
Material from May 28 for Quiz #4 on June 4
Below are the main things from the book that might be on the quiz along with other
discussion in class and some issue in the identification of weed species.
review Quiz 1, Quiz 2, and Quiz 3.
Chapter 5, The plant system (+ lecture)
Plant structures (continued in #6, below)
Know the parts of the flowering plant (in contrast gymnosperms and nonvascular
plants), e.g., stems (rhizomes, stolons), leaves, roots, etc., etc.
In class, I explained that the fruit is a mature ovary, a “seed” is a mature ovule
(although “seed” more frequently is used as
a unit of dispersal), and the types of
fruits such as berries (including drupes and hesperidia) which are fleshy multi-ovule
fruits, the caryopsis (very important) which is the dry single-ovule fruit of grasses
with the fruit wall usually fused to the mature ovule, capsules (which split open to
dehisce multiple seeds), and a samara which is a winged fruit good for dispersal by
wind. What other kinds of “seed” structures can you think of that aid dispersal, and
You should know (and this is not covered in the book) the parts of the flower, sepals,
petals, calyx, corolla, pistil, ovary, ovule, style, stigma, stamen, anther, filament, and
what they do.
Monocots vs. dicots
Know that the dicots (dicotylendons)
have two seedling leaves which you can see
when dicotyledonous (usually broad-leaved) weeds germinate. Grasses germinate
with only one apparent seedling leaf, and are monocots, however
, what you are
looking at is not truly the seedling leaf but the coleoptile which is a sheath that
protects the emerging shoot.
The true seedling leaf is a specialized structure that
never gets out of the ground.
Other differences are that monocots have flower parts
generally in 3’s versus dicots 4’s and 5’s; monocots have parallel veined leaves, and
dicots have reticulate veined leaves; pollen of monocots has a single furrow or pore,
whereas dicots have three furrows or pores.