Aloes and Lilies of Ethiopia and Eritrea

Distribution and
reproduction
TACCACEAE
DIOSCOREA 319
This family includes only one genus, Tacca, distributed
pantropically, with its centre of variation in SE Asia
and Polynesia. It is a unique and systematically isolated
family, but with connections to Dioscoreaceae.
TACCA J.R. & G. Forst.
The genus includes tall herbs, up to 2 m, growing
from tuberous rhizomes. The leaves have long petioles
and are often strongly dissected, a very rare trait for a
lily, more commonly found in the family Araceae. The
inflorescence is umbellate with rather inconspicuous
flowers, subtended by long prominent involucral bracts.
The flowers are bisexual, regular with 3 + 3 united tepals
and 3 + 3 stamens inserted on the corolla tube. The
filaments are short, wide and flattened, extending into
a hoodlike structure covering the anther. The ovary is
inferior with 3 well developed stigmatic branches, and it
develops into a berrylike fruit.
The genus includes c. 10 species which are widely
distributed in the tropics. Only one species is found in
Africa. The flowers have unpleasant smell that attract
carrion and dung flies that act as pollinators. The
hoodlike structures on the stamens may create traps for
insects. Birds are probably involved in the seed dispersal,
efficient enough to disperse the species over large areas.
Since the plants are usuful to man it is probably also
spread by humans. The seeds have a spongy seed coat
with a sweetish taste. The tubers are used for food (starch
content up to 27%) and as medicine. They also include a
bitter substance, taccalin, that has to be removed before
the tubers are eaten. They are traded under the misleading
name of East Indian Arrowroot.