LAB 5: Angiosperm Growth and Reproduction
Xylem (water and nutrients up the root) and Phloem (sugars and metabolic products
down the leaves) form vascular bundles; which can contain vascular cambium.
No vascular cambium in Monocotyledones; therefore secondary growth does
Primary Growth: derived from the apical meristems; roots and stems elongate
Secondary Growth: derived from the lateral meristems; increase in girth (diameter)
1. Procambium: vascular tissue system (xylem, phloem)
2. Ground meristem: ground tissue system (cortex, endodermis, pith)
3. Protoderm: dermal tissue system (epidermis)
The vascular cambium is meristematic; cells retain the power of division.
Secondary phloem on the outside
Secondary xylem on the inside
Annual growth ring of xylem is formed from the vascular cambium each
growing season; narrow rings may mean dry year or poor growth due to
Spring wood has a larger diameter than Summer wood.
Anigosperms are seed plants with ovules enclosed within ovaries
A structure composed of several flowers is called an inflorescence
Complete flowers: contain sepals, petals, stamens and carpels
Incomplete flowers: lacking at least one of these LAB 5: Angiosperm Growth and Reproduction
Sepals: protect the flower when in bud
Corolla: colored petals
Stamen: consist of a stalk, filament which holds the anther (pouch that contains
Pistil: consists of individual carpel (contain a stigma; where pollen lands and a style;
interconnecting channel and a basal ovary; containing two or more ovules
Consist of an ovule with megasporangium; megaspore mother cell divides by meiosis
to produce four haploid megaspores; further produces eight nuclei.
Lily: produces a triploid nucleus (3N – three sets of chromosomes)
Each ovary has three locules, each locule has two ovules
What is the maximum number of megaspore nuclei you would expect to find in one
There should be no more than four megaspores, each the product of meiosis.
Can you find a micropyle in an ovule? How many integumentary layers can you
The micropyle attaches the ovule to the ovary.
What is the maximum number of nuclei possible in one embryo sac?
No more than eight. The largest the female gametophyte gets is seven cells large,
with eight nucleii.
What reasons can you give to explain the presence of less than the maxium? The
egg nucleus is located near the microphyle together with two other nucleii
Two reasons. First, the embryo sac, or female gametophyte, was sliced before
being mounted on the slide, and the cut may simply have been on a plain other
than where all the nucleii are found. Second, and antipodal cells will degenerate
and if the gametophyte had reached this stage, these three nucleii would no longer
Consist of four pollen sacs divided by meiosis to produce haploid microspores; further
divided to produce a generative nucleus and tube nucleus.
How many pollen chambers are there in each anther?
How many nuclei can you see? LAB 5: Angiosperm Growth and Reproduction
There will be two nucleii, a generative nucleus and a tube nucleus.
Pollination and Fertilization:
Pollination is the transfer of pollen grains from the anther to the stigma
Self pollination = single flower