Rosaceae-1

We will use the Rose Family

to explore some important variations in flower structure and relate these to fruit types. This family is one of the most importat fruit-producing taxa, and most of the commercial fruits are well known. The most common examples of this taxon do not grow in the tropics. However, some ornamental roses can be grown in Hawaii.

The Genus Rubus includes blackberries and rasberries. There is a native Rubus species that is being displaced by an alien race and this is an area of concern for Conservation Biologists.

A] This Rubus flower has Five Petal, Many Stamens & Many Simple Carpels in its Apocarpous Gynoecium

C] Another species with relatively large Carpels. The Stigma is readily visible for each Carpel. Note the Green Sepals.
D] Microscopic Image of a Rubus Flower Bud. Relate this to all of the macrophoto to the Right!

E] Rubus flower post pollination. The Ovary of each Carpel is swollen due to successful fertilization. Note the withered Stigmas & Styles.

F] Long Section through a Fragaria (Strawberry) flower: Compare with the Image to the Left

G] The Finished Product

H] A closer inspection reveals the fact that the fruit is composed of many fruitlets that developed from each simple carpel. This is an Aggregate Fruit.

Strawberry is in the genus Frageria. I cheated and used the long section of a Fragaria flower above. The flower structure is nearly identical to Rubus at the outset. However, it is the Receptacle of Frageria which becomes fleshy and is regarded as the "fruit". The carpels become tiny dry indihescent fruits called Achenes.

Strawberry Plants	Strawberry Flower Longitudunal Section	Long section through a flower bud	High magnification showing part of the Gynoecium
Strawberry Fruits: The bulk of this Accessory Fruit is derived from the swollen Receptacle. The true fruits are the tiny, seed-like achenes on the surface.		Close-up of a Strawberry Fruit

This is a type of "Accesory Fruit" because other floral parts besides the Ovary wall are part of the fruit.

Refer to the Rubus illustrations and label the important parts of Fragaria yourself!

I was really enjoying this lesson up until NOW!!!!

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