Friday, October 15, 2010

Lab 4 - Eurosids II: Brassicaceae & Malvaceae


The signature characteristic of the Brassicaceae is its cruciform (X-shaped) arrangement of petals.

Here is pair of flower from Brassica.

Similar to the petals of the Caryophyllaceae, these petals also have a narrow region we referred to as "Claw".
Once the petals and sepals are removed, 6 stamens are revealed. 
Two of the stamens are on a lower plane, while the other four on are a higher plane. We call this condition tetradynamous

One of the fruit types in this family is the silique. They are thin and long therefore 'sleek' [from our TAs Chris and Chris]
The membrane across the ovary is the replum (right: the membrane separating the 2 rows of seeds).

The seed arrangement shown above is "uniseriated" meaning they are arranged in a single line

These are silicles from Lunaria or the money plant.

The silicle can be taken apart. The 2 outer pieces are "valves" and the inner dividing membrane is the "replum".

The heart shaped fruits of Capsella.

MALVACEAE - Mallow (cotton) Family

Cotton plant, a species from the Genus Gossypium.

A Malva flower.

From the transverse section we can see many of the floral parts. Note the branched style/stigma, anthers and staminal tube that is epipetalous.

A Lavatera flower, with linear style/stigma.

A cross section through the fruit (a schizocarp) reveals 10 carpels.

A lobed leaf of the cotton family.

On the underside (lower side) of the leaf is covered with stellate hairs (trichomes).

More stellate trichomes. (click on any image to enlarge)

Flower of a Hibiscus.
Look carefully at at the flower base, you may notice 2 layers of sepals. The lower one is actually an involucral bract. Also note the [slightly] branched style and stigmas.

No comments:

Post a Comment