seed that is eaten by vertebrates. Some rodents and birds collect large numbers
of seeds for storage, often by burying them, thereby dispersing the seeds
effectively. Otherwise, with no active dispersal, dormancy of the seeds will
mean that they can be dispersed by rain or wind or mud on the feet of animals.
Many indehiscent fruits are dispersed by animals. The smaller fleshy fruits
can be ingested whole by mammals or birds, and the seeds will be defecated or
regurgitated elsewhere. With larger fruits or those with larger seeds, vertebrates
will often discard the seeds. A fleshy surface to the seed has the same effect. Dry
indehiscent fruits may disperse by becoming attached to mammals. Bursmay
be formed by hooked outgrowths from the ovary wall or persistent styles elon-
gating during fruit growth and becoming hooked. The dispersal unit of some
grasses is the fruit with surrounding persistent bracts, which enlarge and attach
themselves with sharp points or teeth.
Other indehiscent fruits are dispersed by the wind. The fruit may take the
form of a sail, as in maples (Acerspecies) that may be blown for some distance,
the fruit spinning as it descends. Many composites have persistent sepals that,
when in flower, form a ring of short hairs but as the fruit is set these grow to
form an effective feathery sail for dispersal.54 Section D – Reproductive anatomy
Oil gland Pericarp10 mm Juice sacsSeedFig. 2. Cross section of a citrus fruit.