Platymiscium gracile Benth.

Klitgaard, B. (2005). Platymiscium (Leguminosae: Dalbergieae): Biogeography Systematics, Morphology, Taxonomy and Uses. Kew Bulletin, 60(3), 321-400. Retrieved from http://www.jstor.org/stable/4111062

Type

Peru. San Martin: near Tarapoto, Oct. 1855, Spruce 4228 (lectotype K; isolectotypes BM, C, F, G, GH, K, LD, NY, P, RB, S, W; photo of lectotype C, F, GH, MO, NY, S).

Morphology General Habit

Tree to 12 m tall; internodes of new shoots hollow with ant holes

Morphology Leaves

Leaves opposite or 3-verticillate, 5 - 7- foliolate; vegetative parts glabrous; leaf axis 3.5 - 8 cm long, rachis usually shorter than or as long as petiole; stipules oblong, 5 - 10 x 1 - 3 mm, caducous; stipels not seen; bud scales covering apical meristem (including both inflorescence and leaf buds) linear, larger than stipules; leaflets elliptic to broadly elliptic or obovate to narrowly obovate, distal leaflet larger than others, 3.5 - 8.5 x 2 - 5.5 cm, base rounded or acute, apex acuminate, veinlets of areoles with sharp edges not intermixed with dots, primary vein flush with upper surface, mid green, upper surface glossy, lower surface dull

Morphology Reproductive morphology Inflorescences

Inflorescences of long, pendulous, lax, axillary, simple up to 50-flowered racemes occasionally with secondary branching (both types can be on short shoots), with one to several inflorescences per leaf axil; inflorescence axis slender, smooth, matted pubescent, (3 -)6 - 14(- 18) cm long including an up to 2 cm long peduncle; bracts oblong, 0.5 - 1 x 0.25 mm, concave, appearing confluent with rachis, pilose along margins, caducous before flower fall; bracteoles narrowly triangular, 1 x 0.5 mm, connate basally, pilose along margins, caducous before flower fall

Morphology Reproductive morphology Flowers

Flowers 5 - 8 mm long, slender, pedicellate to sessile; pedicels 1 - 2 mm long, if present, matted pubescent, not articulated at calyx base, persistent after flower fall; calyx cup-shaped, 2 - 2.5 mm long, robust, glabrous, pilose along teeth margins, base acute, abaxial three teeth triangular, acute, adaxial two connate for 1/2 their length, acute; corolla bright yellow; standard cordate, 4.5 - 6 x 3 - 4 mm, short-clawed, with a brown nectar guide; wing petals 4.5 - 6 x 2 - 3 mm, long-clawed; keel petals 4.5 - 5.5 x 1.5 - 2 mm, long-clawed, adnate for a short distance along lower margins, glabrous; stamen filaments fused for 1/2 their length, occasionally the vexillary stamen is only fused at base; anthers monomorphic; ovary long-stipitate, glabrous

Morphology Reproductive morphology Fruits

Samara narrowly elliptic, 5 - 6 x 2 - 2.5 cm, base and apex acuminate (base tapers into stipe); stipe to 5 mm 369 long; exocarp green when immature, hard, glossy, sand-coloured at maturity, glabrous; seed not observed.

Distribution

Platymiscium gracile is endemic to the area around Tarapoto in the Department of San Martin in Peru. It is only known from the type and two other collections.

Ecology

In riverine forests on the lower slopes of the Andes, at 500 - 1000 m.

Phenology

Flowering, young fruits, and fruits from previous season have been recorded in October. While flowering the trees develop new leaves and bear the samaras from the last season. While in fruit they have mature leaves.

Conservation

CR A2cd - critically endangered because of a population size reduction of 80% over the last 10 years due to a decline in area of occupancy, extent of occurrence and/or quality of habitat, and due to actual and potential levels of exploitation.

Note

This species flowers prolifically and most young fruits are destroyed by insect attack. The standards seem not to reflex during anthesis, or they reflex early and return to the original position after pollination and during fruit set. Some collections from the Venezuelan State of Bolivar (Blanco 244, Blanco 467, Blanco 468) have formerly been identified as Platymiscium gracile, but in this revision they are referred to P. pinnatum subsp. pinnatum var. diadelphum, which is the taxon that superficially resembles P. gracile the most. Platymiscium gracile has very characteristic long, lax, elegant racemes with almost sessile flowers, and oblong stipules.

IUCN Red List of Threatened Species https://www.iucnredlist.org/species/36791/10013986

Conservation

VU - vulnerable