Jubaea chilensis (Mal.) Baill.

Arecaceae (Palmae)

The family Arecaceae is a large group comprising approximately 2,500 arboreal species to be found throughout equatorial, tropical, and subtropical areas of the world where they feature as a very peculiar element of the landscape. The main geographical areas having played the role of differentiation centres are Africa’s equatorial coasts, the Indonesian region, the Sunda Isles, Oceania, Brazil’s coasts, Amazonia, and the Antilles. It was during the Cretaceous Period that this group had its largest diffusion and differentiation, leaving behind several fossil remains of trunks and leaves.

Habits of palms are quite typical, in that they are characterised by a tall, unbranched stem (up to 80 m tall in the genus Cocos), or, rarely, by a dichotomous branching stem (Hyphaene), and of the same diameter all along from base to top; at apex it bears a rosette consisting of coriaceous, either palmate or pinnate, leaves, up to some metres long. The stem may remain quite slender, in which case it turns to a creeping habit (Calamus), or otherwise it may be very short in acaulescent species (Phoenix acaulis). Another feature peculiar to this family is that the stem reaches its ultimate growth in diameter before it starts its growth in height. Indeed, palms lack any secondary growth. Inflorescences are spadix-like, at first enveloped by a spathe or by leaf sheaths opening up at anthesis. Flowers are usually unisexual and derive by abortion from hermaphrodite flowers. In monoecious species male flowers are borne apically on the inflorescence, female flowers are borne basally. Proterandry ensures cross-fertilization. Flowers are mostly trimerous and pentacyclic. Their perigonium is made of two whorls consisting of three usually membranous tepals. In male flowers the androecium consists of three stamens in two whorls; however, some taxa depart from this pattern, as the number of stamens may range from three to nine to many. Female flowers bear a superior tri-unilocular ovary, consisting of three carpels, either free or connate, each bearing one ovule. The most typical floral pattern of the family is the following:

P 3+3, A 3+3 G 3

The fruit may be either a berry (Phoenix) or a drupe (Cocos). One fertilized locule only carries on developing, whilst all others wither, so that the fruit contains one seed only. Pollination is mostly anemophilous, accordingly, the plant produces a large amount of pollen for this purpose. There are also a number of entomophilous species whose spathe may give off some kind of scent in order to attract pollinators. One may distinguish between monocarpic species, on the one hand, featuring inflorescences borne terminally on the axis; they live a number of years without reproducing, then they die after blooming (Corypha). On the other, there are polycarpic species featuring axillary inflorescences and able to flower several times.

The family is traditionally divided into a number of subfamilies: a) Phytelephasieae, characterised by flowers without a perianth, a large number of stamens in male flowers and female flowers bearing a multilocular ovary (4-9 locules), infructescences (Phytelephas); b) Coryphoideae, exhibiting floral characters typical of the family: free carpels, berry-like fruits, pinnate or fan-shaped leave (Phoenix, Chamaerops, Trachycarpus, Livistona, Sabal, Washingtonia; c) Borassoideae, characterised by fan-shaped leaves, perianth typical of the family, syncarpous ovary (Hyphaene, Borassus, Lodoicea); d) Lepidocaryoideae, characterised by syncarpous ovary and fruits covered with imbricate scales (Raphia, Metroxylon, Calamus); e) Ceroxyloideae, characterised by syncarpous ovary and pinnate leaves (Arenga, Ceroxylon, Areca, Cocos); f) Nipoideae, characterised by male flowers bearing three connate stamens, and unilocular ovary (Nipa).

The Arecaceae include plants of enormous economic importance for human beings. Particularly, a large number of foodstuffs are made from the coconut palm (Cocos nucifera) to be found along equatorial sea coasts in the Old World. Indeed, fats, oil, wine, and coconut milk are extracted from the drupe, known as coconut, whose endocarp hollow is filled with a huge albumen and a kind of liquid known as ‘milk’. Its buds are employed as vegetable to make salads, its trunk as timber. Phoenix dactylifera, the date palm, is of great economic importance too, notably in the Maghrebian regions, as it yields huge amounts of fruits (berries). Several species are, on the other hand, employed in the production of vegetable fibres (Sabal, Chamaerops, Trachycarpus, Borassus, etc.), Other species, characterised by corneous endosperm, are employed in the production of the so-called "vegetable ivory" (Phytelephas macrocarpa). A very large number of palms are also used in our milder climate regions to provide with treres parks, gardens, squares, and avenues. Among the most widely used to this end, Phoenix canariensis, P. dactylifera, Washingtonia filifera, W. robusta, Syagrus romanzoffiana, Trachycarpus fortunei, etc. should be mentioned.

In Italy, the only spontaneously growing species is Chamaerops humilis not very conspicuous in size, to be frequently found along the coasts of South Italy and over the main islands, where it thrives on coastal areas contributing to the constitution of the thermo-xerophilous maquis belonging to the Oleo-Ceratonion formations.

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