Tall-type coconut varieties from the Pacific region

By R. Bourdeix. 
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The Tall-type coconut varieties, sometimes referred to as var. typica (Nar.), are widely distributed, generally grow more than 50 cm annually, flower at 6-10 years with an economic life of 50-60 years.
Generally, Talls, being protandrous, shed pollen prior to stigma receptivity. They are generally considered as allogamous. Nevertheless, selfing is possible through inter-spadix pollination because of the overlapping between the female phase of an inflorescence and the male phase of the next inflorescence. The speed of emission of inflorescences varies according to genotype and environment, with a great seasonal variation; so does the selfing rate. 
The petiole or leaf stalk is directly attached to the stem which naturally falls when it reaches the tail end of its mature phase leaving leaf scars on the trunk. A rough estimate of the age of the palm can be made by counting the leaf scars on a coconut trunk. In its prime, a coconut palm may produce 14 leaves a year but in old age, this number tends to be less; and suggested that an average of 12 is probably reasonable as a basis for estimating age, but this may also vary depending on the genotype (Child, 1974).
The aspect of the trunk also helps to estimate the age of the coconut palm. Sometimes, the stem widens at the bottom to form a bole that increases its resistance, particularly to cyclones. The stem is relatively smooth and pale in colour, with regular markings: each frond produced by the palm leaves a crescent-shaped leaf scar. It is possible to distinguish between the two types of coconut palm, Talls and Dwarfs, by the gaps between the scars. In Tall palms, the gap between two leaf scars is more than 5 cm, whereas it does not exceed 2.5 cm in Dwarfs.

Tall varieties are generally quite heterogeneous. Nut form and colour vary from one palm to another. Of the varieties described, it is possible to recognize regional types: Small elongated fruits with a large proportion of husk for Africa and India; very large elongated fruits with a large proportion of husk in the pacific region, known as Niu afa, Niu Kafa or Niu Magimagi; large round fruits in Asia;  nippled fruits on Pacific islands and in Papua New Guinea, etc. For example, in the Rennell island Tall variety some individuals are very easy to recognize: the enormous pear-shaped fruits terminating in a proeminent nipple leave no room for doubt!  Yet in that same Rennel Tall variety, other palms produce rounder fruits on which the nipple is much less visible, if at all; those individuals are much harder to identify. Even an experienced specialist has considerable difficulty in distinguishing between varieties with large fruits, such as the Panama Tall, Markham Valley Tall or Cambodian Tall.

The sexuality of the plants is very inventive! Each coconut palm is bisexual and produces inflorescences bearing both female and male flowers. It can therefore pollinate itself; moreover, most Dwarf coconut palms reproduce in that way. In Tall coconut palms, the pollination mechanisms are more complicated. To understand them, it needs to be known that the female phase of an inflorescence corresponds to the period when female flowers are receptive, and the male phase begins as soon as the inflorescence opens and ends when the last male flower falls. In some varieties, all the male flowers ripen and fall before the female flowers are receptive. In that case, cross-pollination takes place: it necessarily involves two different parents. But another phenomenon further complicates this mechanism. It is also possible for pollination to take place between two successive inflorescences on the same palm. The female phase of a given inflorescence may partially coincide with the male phase of the following inflorescence. The coconut palm is therefore a species in which two different reproduction methods exist side by side.