Desmoncus interjectus Henderson, Phytotaxa 35: 26 (2011)

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Distribution

Map uses TDWG level 3 distributions (http://www.nhm.ac.uk/hosted_sites/tdwg/geogrphy.html)
Colombiapresent (Henderson, A., A revision of Desmoncus (Arecaceae) in Phytotaxa 35. 2011)A
From 0°00'-0°37'S and 70°11'-72°26'W in Colombia (Amazonas, Vaupés) at 194(160-250) m elevation along margins of blackwater streams (Henderson, A., A revision of Desmoncus (Arecaceae) in Phytotaxa 35. 2011)A

Discussion

  • Taxonomic notes:-Except for its short, recurved, swollen-based rachis spines and peduncular bracts, D. interjectus strongly resembles D. horridus subsp. palustris. This subspecies, as noted above, has rachis spines which are less developed than in other subspecies, and in some cases are abaxial and appear short and recurved, almost like those of D. polyacanthos. In fact, D. interjectus appears more similar to D. horridus than to other species with recurved rachis spines, and its recurved rachis spines may be secondarily derived from straight spines. (Henderson, A., A revision of Desmoncus (Arecaceae) in Phytotaxa 35. 2011)A

Description

  • Plants 6 m tall; stems 2.1 (1.7-2.8) cm diameters. Leaf petioles 2.9(1.0-10.5) cm long; rachises 125.0 cm long, 8.2(6.2-11.0) mm wide, the spines usually <1 cm long, mostly abaxial, recurved with markedly swollen bases; pinnae 10(9-11) per side of rachis, without a beard of spines at the bases, without spinules or dense tomentum at the bases adaxially; basal pinna 23.3(17.0-28.5) cm long, 2.1(1.0-3.0) cm wide; cirri welldeveloped, with acanthophylls, with few spines abaxially, mostly on proximal part only, with no intermediate acanthophylls present, usually with a wide gap between pinnae and acanthophylls. Inflorescences with the rachis angular, slightly twisted, thicker than the few to numerous, closely spaced and spirally arranged rachillae, each rachilla not (or very rarely) adnate to the rachis, subtended by an acute bracteole and with a well-developed axillary pulvinus; peduncles 4.1(2.6-4.8) mm wide; peduncular bracts 28.7(19.0-46.0) cm long, broad, the surfaces deeply ridged, dark brown tomentose, sparsely covered with long, straight or sinuous spines, the bases scarcely swollen but running directly into the ridges of the bract and lying flat against the bract surface, flattened in cross-section, brown proximally and distally, with tomentose margins; rachillae 16(13-18); proximal rachillae 8.5(7.0-11.5) cm long, 1.8(1.2-2.2) mm wide; stamens 8; fruits 14.2(13.5- 15.1) mm long, 10.7(9.8-12.3) mm wide, the surfaces uneven with numerous, subepidermal, short, often branching (Y-shaped) fibers; fruiting corollas less than one quarter as long as fruits, not or scarcely splitting, tending to remain cupular; endocarps narrowly ellipsoid with rounded apices, the pores lateral. (Henderson, A., A revision of Desmoncus (Arecaceae) in Phytotaxa 35. 2011)A

Bibliography

    A. Henderson, A., A revision of Desmoncus (Arecaceae) in Phytotaxa 35. 2011