seashore palm, coco da praia
Stems: Solitary, subterranean (rarely growing above ground, vertically or horizontally). The palm may appear to have multiple stems when several seeds germinate in close proximity to form a cluster. Leaves: Pinnate, 1-1.5 m long, with linear leaflets spreading in multiple planes, grouped in clusters of 2's or 3's. Upper leaf surface, green or waxy gray; undersurface, whitish or silvery. Flowers and fruits: A short, dense spike protected by a woody spathe and not branched. Triads with a central female flower bordered by two male flowers occur at the base of the spike while toward the tip, only male flowers appear. The irregularly spherical to turbinate fruits (1.5-2.5 cm) are densely clustered and yellow green when ripe, sometimes with brown tomentum.
Acrocomia aculeata (as a juvenile before the stem grows aerially, perhaps), but that palm has leaf spines while Allagoptera arenaria is not armed.
Native to coastal Brazil, behind dunes
This is a palm of the seashore, dunes, and dry, open maritime forests; it is tolerant of salt spray and can be seen as a cultivated palm in coastal areas.
Allagoptera arenaria (Gomes) Kuntze
Allagoptera pumila Nees
Cocos arenaria Gomes
Diplothemium arenarium (Gomes) Carv.Vasc. & Franco
Diplothemium littorale Martius
Diplothemium maritimum Martius