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Published In: Hooker's Icones Plantarum 12: 1147. 1873. (Hooker's Icon. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 1/2/2013)
Acceptance : Accepted
Project Data     (Last Modified On 5/13/2014)
Notes:

The genus Stilpnophyllum is classified in the Tribe Cinchoneae, and includes perhaps a half-dozen species of shrubs and small to medium-sized trees found in wet forests in Colombia, Ecuador, and Peru. Stilpnophyllum has been little-known until recently, when Andersson (1994) described several species and the genus was documented in field work by Neill, Vásquez,and collaborators exploring areas with quartzite and sandstone substrates. Stilpnophyllum can be recognized by the combination of its generally tough-textured leaves with the margins usually revolute and with numerous well developed intersecondary veins, its axillary inflorescences with numerous small to medium-sized white flowers, and its woody, rather small, cylindrical capsules with numerous narrow winged seeds. The flowers are white, densely pubescent, and now documented to be distylous; no odor has been described, and it is unknown if they are nocturnal. The capsules are rather distinctive in their dehiscence mode: they are septicidal and open from the top, with the valves curving back but remaining fused at the base and persistent on the infructescence. These capsules are sometimes a little asymmetric in dehiscence, splitting below the apex with one valve retaining the entire calyx limb and the other smaller; however some plants have symmetrical dehiscence and others have variation in this form within an individual inflorescence.

Stilpnophyllum is similar to Pimentelia, which is also found in the Andes in central Peru to northern Bolivia and is also not well known. Andersson (1993) recognized these as separate genera, and distinguished them only by leaf characters. These both have tough-textured leaves, resinous stem apices, and similar stipules, inflorescences, flowers, and fruits, and are both found in similar habitats. Their separation is outlined in the Pimentelia page of this Rubiaceae TROPICOS Project; their separation may deserve re-evaluation. Stilpnophyllum is also similar in general aspect and sometimes habitat to Ladenbergia (especially Stilpnophyllum oellgaardii), which has terminal inflorescences, and to Retiniphyllum, which has stipules that are fused around the stem into a sheath, generally terminal inflorescences, and 5-locular ovaries that develop into drupaceous fruits. Stilpnophyllum can also be confused, especially in bud or young fruits, with Joosia, which is found in the same region: Joosia can be recognized by its leaves with the higher-order venation lineolate (though the venation is not visible in some species) and its generally larger corollas with the lobes induplicate-valvate and markedly crisped or appendaged along the margins.

Author: C.M. Taylor.
The content of this web page was last revised on 3 January 2013.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml

 

Distribution: Wet premontane and montane forests, often if not generally on sandstone substrates, at ca. 1000-2500 m, in the Andes of northwestern Colombia and in southern Ecuador through central Peru. Stilpnophyllum may grow in other areas in western Colombia, but the mountains of that region are not well explored botanically.
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Shrubs and small to medium-sized trees, unarmed, terrestrial, without raphides in tissues, markedly resinous at stem apices, branching at least sometimes sylleptic. Leaves opposite, with tertiary and quaternary venation not lineolate but with numerous well developed intersecondary veins, on lower surface with well developed pubescence domatia at junctions of secondary veins with costa; stipules quickly deciduous, interpetiolar, triangular, generally held erect and flatly pressed together in bud. Inflorescences axillary (i.e., present in both axils of the node), borne with leaves near to well below stem apex, thyrsiform to paniculiform, multiflowered, pedunculate, bracteate. Flowers sessile or subsessile generally in groups of 3-5, small to medium-sized, distylous; hypanthium ellipsoid; calyx limb subtruncate to 5-lobed, without calycophylls; corolla funnelform to salverform, white, densely villous to villosulous internally in tube, in throat, sometimes on lobes, and on margins of lobes, lobes 5, triangular, valvate in bud; stamens 5, inserted in corolla tube, anthers narrowly ellipsoid, dorsifixed near base, included in long-styled flowers and exserted in short-styled flowers; ovary 2-locular, ovules numerous in each locule, imbricated and ascending on axile placentas; stigmas 2-lobed, rather succulent, exserted in long-styled flowers and included in short-styled flowers. Fruit capsular, cylindrical, woody, septicidally dehiscent from apex, valves spreading but remaining fused and persistent at base, sometimes a little asymmetric with capsule apex and entire calyx limb retained on one valve; seeds flattened, small, fusiform, marginally winged, entire to erose, acuminate at the ends or sometimes 2-lobed at one end.

 

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Key to Species of Stilpnophyllum (by C.M. Taylor; this key follows Andersson (1994) but also incorporates additional characters)

1. Stipules 20-35 mm long; leaves 7-11 cm wide, with secondary and intersecondary veins generally different in development and distinguishable; flowers usually 5-15 in compound, very congested cymules....Stilpnophyllum grandifolium

1'. Stipules 2-17 mm long; leaves 0.5-8.5 cm wide, with secondary and intersecondary viens not visible, or visible and very similar in development and difficult to distinguish; flowers 3-9 in simple, subcapitate or umbelliform groups, or occasionally in compound groups.

    2. Leaves rather narrowly oblanceolate, 0.8-2.5 cm wide; branched portion of inflorescence ca. 1 x 2 cm...Stilpnophyllum revolutum

    2'. Leaves elliptic, obovate, or elliptic-oblong.

        3. Calyx limb ca. 1 mm long, lobed for ca. 1/2-2/3, the lobes generally acute; corolla funnelform, with tube 4-5 mm long; capsules generally stiffly chartaceous...Stilpnophyllum lineatum

        3'. Calyx limb 2-3 mm long, undulate to lobed for up to ca. 1/4, the lobes rounded to acute; corolla salverform or tubular-funnelform, with tube 8-9 mm long; capsules woody....Stilpnophyllum oellgaardii

 
 
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