BOTANY Higher Secondary Second Year - Textbooks Online

a large woody bract called spathe. In Corypha umbraculifera
(Kudai panai), the spadix is terminal and it measures about 10 metres. It is
a monocarpic plant. The plants are polycarpic and monoecious (eg. Cocos
nucifera) or dioecious (eg. Borassus flabellifer).
Flower
Bracteate, ebracteolate, sessile, usually unisexual and monoecious or
dioecious, trimerous, incomplete, actinomorphic and hypogynous. In
Borassus flabellifer, the male flowers are smaller than female flowers. In
Cocos nucifera male flowers are densely arranged at the upper portions of
the spike and female flowers are at the base of the spike.
Perianth
Tepals 6 arranged in two whorls of three each, persistent, polyphyllous
or gamophyllous showing valvate or twisted or imbricate aestivation. In
Phoenix acaulis, the tepals of outer whorl are united and valvate while
that of inner whorl are free and twisted.
Androecium
Stamens 6 arranged in two whorls of three each and opposite to
tepals. Anthers are dithecous, basifixed or dorsifixed, introrse and dehiscing
longitudinally. Pistillode is usually present in male flowers.
Gynoecium
Ovary superior, tricarpellary and syncarpous. Ovary trilocular with
single ovule showing axile placentation. In Phoenix acaulis, the placentation
is basal. Style extremely short or absent and stigma three. Staminode is
present in female flowers. In Cocos nucifera, two carpels become abortive
out of three.
Fruit
Seed
A drupe with fibrous mesocarp.
Seed with small embryo and abundant endosperm.
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