Brassicas - The Manual of Seed Saving - page 35

Brassicas
BRASSICACEAE

The brassica or cabbage family contains 350 genera, many of them common in agriculture
and ornamental gardening. The vegetables of the species Brassica oleracea are among the
most important crops in the garden: cabbage, kohlrabi, cauliflower, Brussels sprouts, and
broccoli, among others. The oil, vegetable, and fodder crops of the species B. napus and B.
rapa belong to the cabbage family as well, as do radishes. Other brassicas cultivated for their
tasty, pungent leaves include arugula, garden cress, watercress, and perennial wallrocket.
Many brassicas cannot tolerate heat at all; they thrive in spring and autumn and like cool
sites (north slopes, high altitudes).
Brassicas were formerly known as crucifers, a reference to the fact that the four petals of
their flowers are in the shape of a cross. Brassica flowers are usually yellow (in some cases,
white) and develop into fruits in the form of seedpods.

GENERAL PROPAGATION CHARACTERISTICS
Many brassicas are grown for seed as biennials, though some crops (arugula, radish, cauliflower, broc-
coli) will produce seed in the first year. All brassicas are outcrossers and most are self-infertile, meaning
pollen from a flower on one plant cannot pollinate another flower of the same plant. This condition is a
natural mechanism for promoting genetic diversity, though it also requires that brassicas be grown for
seed in plots of at least 10 to 15 plants. If only one plant is left to flower, it will not produce any usable
seed.

The petals of brassica flowers form the shape of a cross.

Overview of brassicas (cabbage f amily)

COMMON NAME GENUS SPECIES

cole crops: cabbage, cauliflower,
broccoli, savoy cabbage, kohlrabi,
Brussels sprouts, kale, collard greens

Brassica oleracea