Aloes and Lilies of Ethiopia and Eritrea

44 ALOACEAE
Reproduction
Chemistry and
use
the northern and central highlands, north and west of the
Rift valley (for example Aloe elegans, A. pulcherrima,
and A. debrana). The second group includes 9 species
which are restricted to the eastern and SE highlands
and lowlands (for example A. elkerriana, A. harlana, A.
mcloughlinii and a newly described A. welmelensis). The
third group of 6 endemics (for example Aloe gilbertii,
A. otallensis, and A. friisii) are mainly restricted to the
southern parts. The fourth group that includes 4 species
(Aloe clarkei and A. kefaensis, and the newly described
A. benishangulana and A. ghibensis that belong to the
western parts of Ethiopia).
The aloes have long tubular, most often red to yellow
flowers, producing considerable amounts of nectar, all
traits indicating typical adaptations to bird pollination.
The different aloe species have different flowering
periods; some flower over an extended period, thereby
offering a continuous food supply for nectar feeding birds.
Accordingly the aloes make an important contribution
to the bird biodiversity of Ethiopia, especially for the
sun birds. At the same time, the birds are vital for the
pollination of the flowers and seed set.
The flowers are slightly protandrous, which means
that the pollen grains mature and are released before the
stigma becomes receptive, thereby the flowers avoid selfpollination.
When a bird arrives to enjoy the nectar in a
flower, it will either get powdered with pollen or deposit
pollen from earlier flower visits on the stigma.
The stiff erect capsules are only open in the upper part.
This hampers an easy fall­out of the seeds. A strong wind
or a strong kick is required to release or eject the seeds.
These processes ensure that the seeds are thrown some
distance from the mother plant. The function of the thin
arils covering the seeds is not clearly understood.
In addition to reproduction by seeds, several species
have the ability to produce lateral rosettes that may
develop into independent individuals by fragmentation.
The new plantlets are capable of producing new roots,
and this is an important factor for maintaining the
populations. This is often seen in the spatial arrangement
of the individuals, which occur in clusters.
Aloe, the term here referring to the dried latex extracted
from the leaves, has figured in the civilizations of Africa,
Asia, Europe and the Middle East for thousands of years.