Aloes and Lilies of Ethiopia and Eritrea

206 ALOACEAE
Distribution and
classification
Reproduction
Use and
chemistry
ALLIACEAE
The family includes herbs with bulbs, bulb­like corms, or
rhizomes. The underground parts usually produce a smell
of garlic or onion when squashed. Leaves are produced
in a basal rosette, or they are 2-ranked. The inflorescence
is an umbellate or a globose head, subtended by 1–2
membranous bracts. The flowers are commonly regular,
the perianth varying from white to pink, blue, violet or
purple, sometimes yellow. The 6 tepals are more or less
equal. The stamens are attached to the base of the tepals.
The filaments are flattened. The ovary is superior with
nectar producing groves in the walls. The fruit is a capsule
with few to many seeds, often somewhat triangular in
cross section.
The family Alliaceae is mainly distributed in the temperate
regions, both in the southern and northern hemispheres.
Only a few species reach the tropics. It is represented by
c.13 genera and 700 species worldwide. In the Flora area,
it is represented by two genera: Allium and Agapanthus.
The genus Agapanthus, represented by A. praecox, is
only known in cultivation in Ethiopia and Eritrea, and is
not further treated here. The genus Allium is represented
by indigenous and cultivated taxa.
A large number of species with bulbs have vegetative
propagation. Often some of the flowers are substituted by
bulbils that function as vegetative dispersal units.
One of the characteristic features of the family is the
absence of alkaloids which are found in related families as
Amaryllidaceae. Members of the genus Allium are known
to contain sulphur­compounds which contribute to their
particular smell and taste. They also include flavones and
flavonols. In fact, Allium species can be separated into
three groups based on these compounds: those that have
only flavones, those with only flavonols and those with
both. Species of the genus have been in cultivation since
the first periods of agriculture in the Old World. Onions,
garlic, leek, and chives belong in the genus.