Mediterranean Fan Palm

Description

Chamaerops is a genus of flowering plants in the family Arecaceae. The only currently fully accepted species is Chamaerops humilis, variously called European fan palm or the Mediterranean dwarf palm. It is one of the most cold-hardy palms and is used in landscaping in temperate climates. Chamaerops humilis is a shrub-like clumping palm, with several stems growing from a single base. It has an underground rhizome which produces shoots with palmate, sclerophyllous leaves. The stems grow slowly and often tightly together, eventually reaching 2–5 m (10–20 ft) tall with a trunk diameter of 20–25 cm (8–10 in). It is a fan palm (Arecaceae tribe Corypheae), and as such, has leaves with petioles terminating in rounded fans of 10–20 leaflets. Each leaf is up to 1.5 m (5 ft) long, with leaflets 50–80 cm (20–30 in) long. The petioles are armed with numerous sharp, needle-like spines; these may protect the stem growing point from browsing animals. The flowers are borne in dense, short inflorescences at the tops of the stems. The plants usually, but not invariably, are dioecious with male and female flowers on separate plants. The prophyll covers the flowers on the inflorescence until the sexual phase (anthesis) and then splits open apically into two triangular lobes. The number of flowers per inflorescence is highly variable for both male and female plants, depending on the size of the inflorescence. Female flowers are tri-ovulate. At anthesis, as is common in angiosperms, both male and female Chamaerops humilis plants attract their pollinators with chemical compounds, but an unusual feature is that their scents are released by the leaves, and not by the flowers. Towards the end of anthesis, weevils leave the plant and seek a new host plant, again either male or female. Larval development of the weevil Derelomus chamaeropsis occurs within rachises of inflorescences of male plants during autumn and winter. At the beginning of the next flowering period, adult weevils emerge from the dry and brittle stems of old inflorescences of the previous year of male plants only. Those that hatch in female plants die without concluding their development. This is because the palmettos are adapted to prevent the pollinating weevils from destroying the female inflorescences with their burden of seed. Weevils have been shown to lay eggs within female inflorescences, but as soon as seeds start to develop, eggs or larvae fail to continue their life cycle.