Brassicaceae at Cambridge

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Last summer I spent a wonderful week in Cambridge, on the Flowering Plant Families course at the Cambridge University Botanic Garden.  It was a warm sunny week, and around 20 of us sat at microscopes in a classroom, the windows open to let in a summer breeze.  We had tea, biscuits and fresh plant material in jam jars around us.

DSC_0867

jars of fresh material and suggested reading

classroom

This is the first in a series of plant identification blog posts, based on what I learnt at Cambridge.

One of the simplest plant families to start with is the cabbage family – Brassicaceae (pronounced brass ick ay see).

This is one of the simplest families to recognise as it has distinctive characteristics which are repeated.  The characters are

Sepals (calyx): 4

Petals (corolla): 4

Androecium (stamens): 6 (2 short, 4 long)

Gynoecium (carpels): 2 fused

The fruit is a siliqua – a pod like capsule with 2 united carpels.

I pulled the flower apart and laid it out so the parts are easy to see:

Rocket - Eruca sativa, Brassicaceae

This plant family is also called Cruciferae. This name comes from the cross (or crucifix) shape made by the four petals. It is easier to see in some species than others.

It is a family of annuals or perennial herbs, which contain mustard oils (glucosinolates) which give cabbage and Brussels sprouts their strong flavour.  Leaves are alternate and can be simple or toothed/lobed.

There are many economic uses – food like cabbage, rocket, broccoli and cauliflower, plus mustard and cress.  Oil is obtained from oil seed rape.  Other family members are grown as ornamental garden plants, such as honesty, stocks and wallflower.

eruca sativa

This is a herbarium sheet in the Manchester Museum of Eruca sativa (rocket). It was collected in St-Anne’s-on-the-Sea, Lancashire by Charles Bailey, one of our big collectors, in 1907. The handwritten number starting with EM, just above the printed label, is the database number we give each of our specimens.

This is a good, simple guide to the parts of a flower http://www.amnh.org/learn/biodiversity_counts/ident_help/Parts_Plants/parts_of_flower.htm

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