19. Diogenesia SLEUMER Notizbl. Bot. Gart. Berlin-Dahlem 12: 121 (1934). -- Type: Diogenesia
octandra SLEUMER.
Eleutherostemon HERZOG, Meded. Rijksherb. Leiden 27: 22 (1915), non KLOTZSCH (1838).
-- Type: Eleutherostemon racemosum HERZOG [=Diogenesia racemosa (HERZOG) SLEUMER].

References: SMITH, A. C., Studies of South American plants, XII. Contr. U.S. Natl. Herb. 29(8): 350--355 (1950). -- SLEUMER, H., A revision of the genus Diogenesia. Notes Roy. Bot. Gard. Edinburgh 36(2): 251--258 (1978).

Small shrubs, usually epiphytic, with slender, often elongate and pendent branches, occasionally climbing. Leaves alternate, subcoriaceous to coriaceous, margin entire, 3--5-plinerved, short-petiolate; bud scales generally distinct (=Sleumer's pseudostipule). Inflorescences axillary, in few- to many-flowered fascicles or racemes, very rarely reduced to a solitary flower; pedicel slender, bibracteolate about midway along pedicel. Flowers 4--5-merous, without odor; aestivation valvate; calyx continuous with pedicel; hypanthium campanulate, rounded at base, truncate at apex, smooth or indistinctly 5-ribbed; limb and lobes short, suberect; corolla cylindric, urceolate or campanulate, shortly lobed to -partite halfway; stamen 4, 5, 6, 8 or 10, equal in length, as long as or slightly shorter than corolla; filaments distinct, longer or shorter than anthers, lacking spurs, pubescent; anthers oblong, lacking disintegration tissue; thecae smooth or faintly granular; tubules as long as or longer than the thecae, dehiscing by an introrse oval pore or cleft; pollen lacking viscin threads; nectariferous disc usually prominent, thick-annular, entire or crenulate, rarely conical; ovary inferior; style slender, equalling the corolla in length or long-exserted; stigma truncate. Fruit a juicy berry, subglobose, when immature pericarp thin and brittle, when mature subcoriaceous, usually purple to blue-black; seeds numerous, the embryo green.

A neotropical genus of 13 spp., ranging from Venezuela to northern Bolivia, closely related to Sphyrospermum.


Key to Species of Diogenesia
1a.
Leaves amplexicaul, auriculate-cordate at base
..........................................................................................D. amplectens
1b.
Leaves not amplexicaul, subcordate or rounded to attenuate at base.
2a.
Flowers solitary.
3a.
Pedicel 10--13 mm long; corolla 10--13 mm long; filaments 5--6 mm long; anthers including tubules 3.5--4 mm long
.......................................................................D. oligantha
3b.
Pedicel 20--30 mm long; corolla 18--22 mm long; filaments 13 mm long; anthers including tubules 7--7.5 mm long
......................................................................D. gracilipes
2b.
Flowers in few- to many-flowered fascicles or racemes.
4a.
Stamen 4 or 5; nectariferous disc pulvinate or conical, conspicuously elevated; bracteoles usually located below middle of pedicel; rachis usually 5--7 mm long; staminal filaments long-pilose; corolla lobes very conspicuously deeply cut at anthesis, 2--3 mm long
......................................................................D. floribunda
4b.
Stamen (6--) 8 or 10; nectariferous disc annular, low, or rarely conical-elevate; bracteoles usually located above middle of pedicel; rachis usually > 10 mm long; staminal filaments short-pilose; corolla lobes shallowly cut not conspicuous, 1--2.5 mm long
.....................................................................D. octandra