Difference between revisions of "Dypsis ambilaensis"

|image=C6b4c92e-8996-4548-84dd-cc38e50ecb68.jpg

|image_caption=Ambila-Lemaitso, Madagascar, photo by Dr. John Dransfield, edric.

|genus='''''Dypsis'''''

|species='''''ambilaensis'''''

Endemic to Madagascar's East Coast, Tampina to Ambila- Lemaitso, south of Toamasina. Coastal forest on white sands at low elevations.

Slender, clustering undergrowth palmlet, 1-3 m tall. STEMS about 5-8 mm in diam., internodes 7-18 mm long, green when young, densely covered with caducous dark brown to black scales, old internodes ± blackish. LEAVES about 7-8 in the crown; leaf-sheaths 6-8 x 0.9-1.5 cm, striate, sparsely covered with caducous black scales near base, densely covered distally, leaf sheath mouth with 2 triangular, membranous auricles 3-5 x 3-4 mm; leaf about 25-40 cm long; petiole absent or to 7 x 0.2-0.4 cm; rachis 15-22 cm long, abaxially covered with blackish scales; blade entire bifid, to 22 x 11 cm, the apical lobes to 13 x 5.5 cm, or divided into 2-4 pairs of narrow to broad, ± sigmoid leaflets, the narrowest at the base, the mid-leaf leaflets usually the broadest, leaflets ranging from 7-20 x 0.5-4 cm, the apical pair (or the two lobes in the entire, bifid leaf) shallowly lobed distally, adaxial surface glabrous, abaxial surface with bands of caducous brown scales, numerous punctiform scales and sometimes with long narrow ramenta along main ribs. INFLORESCENCE interfoliar, only slightly exceeding leaves, branching to 2 orders; prophyll 12-25 x 0.4-0.5 cm, bearing sparse to dense laciniate red-brown scales or glabrescent; peduncle 17-25 x 0.2 cm bearing scattered laciniate dark redbrown scales; peduncular bract exceeding the prophyll by about 2-6 cm, otherwise similar; rachis 9- 26 cm, sparsely to rather densely covered in red-brown laciniate scales; first order branches 10-27, at least about a half of them branching to the second order; rachillae about 16-55, slender, 3-5.5 cm, about 0.7 mm in diam., glabrous, bearing triads about 2-3 mm distant, each subtended by a low rounded rachilla bract, the bract usually with laciniate redbrown hairs to 1 mm long along margin. STAMINATE FLOWERS at anthesis about 1 mm in diam., red, with slight fecal smell; sepals unequal, broad, imbricate, 0.5 x 0.4-0.7 mm; petals rounded triangular, striate, 0.8 x 0.6 mm; stamens 3, antepetalous, filaments connate at the very base, free portion ± triangular, 0.3 x 0.3 mm, anthers didymous, 0.3 x 0.1 mm, staminodes minute, about 0.1 x 0.1 mm; pistillode a low dome. PISTILLATE FLOWERS globular, about 1.1 mm in diam.; sepals irregularly rounded, imbricate about 0.5 x 0.5 mm; petals broadly triangular about 1 x 1 mm, valvate, imbricate only at the base, striate; staminodes 5-6, irregular, about 0.15 x 0.1 mm; ovary rounded, about 1 mm in diam., stigmas 3, thread-like, about 0.15-0.2 mm. Immature FRUIT curved; mature fruit somewhat curved, red, 10-15 x 4.5-5 mm, striate when dry. SEED 8 x 3.5 mm; endosperm homogeneous, embryo lateral, about 2 mm above base. Editing by edric.

This species is superficially very similar to D. forficifolia and can only be separated with certainty if staminate flowers are available. In D. ambilaensis there are three antepetalous stamens and three staminodes (i.e., this species belongs to the previously recognised Dypsis § Trichodypsis), while in D. forficifolia the stamens are antesepalous and there are no staminodes (i.e., this species belongs to Dypsis § Dypsis). So far, D. ambilaensis has been found only in coastal forest on white sands near Ambila-Lemaitso and Tampina, south of Toamasina. It is particularly confusing that D. forficifolia can grow in an apparently identical forest type along the coast further to the north, near Mananara. A few of the staminate flowers on the specimen Dransfield et al. JD6444 appear to have six fertile stamens (see also Dypsis thermarum). (J. Dransfield and H. Beentje. 1995).

 

This is a small palm of the undergrowth of white sand forest developed on raised beaches behind the East Coast. It appears superfically to be almost identical to D. forficifolia. Unfortunately, there are no easy ways to identify the two species, without dissecting the flowers and observing the stamens. However, we have noted that the two species appear to be geographically separated. Ambila-Lemaitso, the type locality, is the root of the species name. (J. Dransfield and H. Beentje. 1995).

Conservation: Endangered. Known only from the coastal white sand forests south of Toamasina, forests that are of very limited extent and much prone to damage by fire, as well as to development. (J. Dransfield and H. Beentje. 1995).

*[http://www.plantapalm.com/wianame.htm Pronunciation Key]

 

Special thanks to Geoff Stein, (Palmbob) for his hundreds of photos, edric.