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Published In: Journal of Botany, being a second series of the Botanical Miscellany 3: 270. 1841. (J. Bot. (Hooker)) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 12/10/2012)
Acceptance : Accepted
Project Data     (Last Modified On 12/18/2012)
Notes:

Leptostigma was studied by Fosberg (1982), who recognized six species found in South America and the southern Pacific. It is characterized by its low, herbaceous, creeping habit; raphides in the tissues; petiolate, opposite, generally ovate leaves; stipules that are fused to the bases of the petioles, persistent, and fimbriate or lobed with the apices of the segments generally glandular; bisexual, subsessile to pedunculate flowers that are ebracteate and solitary or three and bracteate at the stem apices at anthesis, later becoming displaced to pseudoaxillary by growth from one of the axillary buds; calyx limb with variously 4(-6) lobes, with sometimes some of them reduced; funnelform, pale green to whitened or yellow, funnelform corollas with 4(5) lobes that are valvate in bud; 4(5) stamens inserted near the bse of the corolla, anthers basifixed and exserted on well developed filaments; style short with stigmas linear, long, and partially exserted; ovary 2-locular with ovules solitary, basal, and erect in each locule; and drupaceous fruits that are rather dry at maturity and contain two planoconvex, rather hard pyrenes, each with one seed. The species of this genus do not appear to be locally common in general. Fosberg noted that the fruits are generally leathery or dry rather than succulent. The leaves of some plants are apparently glandular on the lower surface. Andersson (1993" p. 15, fig. 1) presented a very useful illustration of Leptostigma pilosum. Overall Leptostigma is not well known (see in particular the comments on the Leptodermis weberbaueri project page); however Ramírez & Alberdi presented a detailed study of the ecology of Leptodermis arnottianum.

Fosberg (1982) and Andersson (1993) described the flowers as bisexual, which seems accurate, even though this tribe and subtribe are sometimes described as having only dioecious flowers (however Subtribe Coprosminae Fosberg was originally diagnosed as having either bisexual or unisexual, dioecious flowers). The pollination mode of these species, or at least the South American species, is not accurately known. The corollas are rather well developed, but the stigmas and anthers elongated and well exserted, as in anemophilous flowers; both the filaments and the stigmas are long and slender, though the filaments do not appear to be particularly flexuous. Andersson described the flowers as "homostylous", but this is at best oversimplified and perhaps not quite accurate. The flowers of Leptostigma pilosum are now documented by several collections, more than Andersson saw, on which the corollas are first relatively small with one sexual structure exserted; subsequently the corollas enlarge, often to twice the size of younger flowers on the same stem, and the sexual structure that was first exserted is elongated more and the other sexual structure also is exserted. In some flowers the stigmas apparently emerge first and are longer than the fully developed stamens, while in other flowers the stamens emerge first and remain positioned above the stigmas. More study will be needed to fully understand the situation here. Fosberg noted that in some species (or plants), the ridged fruits more or less disintegrate leaving the pyrenes held within the persistent fibrous ridges.

Leptodermis is similar to Nertera and Mitchella, and Fosberg clarified their limits; he also synonymized Corynula with Leptostigma. Mitchella can be recognized by its flowers that are fused together in pairs by their ovaries, vs. free flowers in the other genera. Nertera can be separated by its calyx limb that is reduced to a rim or entirely lacking; its shorter filaments, only slightly exceeding the corolla tube; its shorter stigmas, ca. 1-2 mm long; and its succulent to juicy fruits. In the Neotropics Leptostigma is similar in general aspect to species of Coccocypselum, which are found in the same regions; Coccocypselum differs in its salverform corollas, short stigmas and stamens, and larger, bright blue, baccate fruits with numerous small seeds.

C.M. Taylor XII 2012

Distribution: Western South America with several species described from high elevations in the northern to Central Andes and one species in temperate southern Chile, one species in New Zealand, and one species in southeastern Australia.
References:

 

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Prostrate to acending herbs, usually rooting at node, with raphides, unarmed, terrestrial. Leaves opposite, generally isophyllous, entire, without domatia, sometimes glandular on the lower surface; venation not lineolate; stipules interpetiolar and fused to bases of petioles, erect to reflexed, persistent, truncate to triangular, denticulate to erose or lobed, with the 2-7 segments or teeth usually glandular. Inflorescences terminal then later displaced to pseudoaxillary, with flowers solitary and ebracteate or 3, cymose, and bracteate, with peduncles or pedicels often elongating markedly as fruits develop. Flowers bisexual, reportedly homostylous (but see discussion), sessile to pedicellate or pedunculate, apparently diurnal; calyx limb 4-6-lobed or some lobes sometimes reduced, without calycophylls, with lobes sometimes enlarging markedly after anthesis; corolla funnelform, green, whitish green, yellow, or dark red to purple, apparently glabrous inside, with lobes 5(4), valvate in bud;stamens 4(5), inserted in lower part of corolla tube or near its base, exserted on well developed slender filaments, anthers oblong, dorsifixed near base, dehiscent by linear slits; stigmas 2, linear, prolonged and flexuous, exserted; ovary 2-locular, with ovules solitary in each locule, basal, erect. Fruit drupaceous, ellipsoid, leathery to rather dry; pyenes 2, planoconvex, each with 1 seed.

 

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Key to Species of Leptostigma; based on Fosberg (1982)

1. Plants glabrous except pilose on leaf margins; calyx lobes ovate, acute, remaining erect in fruit; temperate Chile.....Leptostigma arnottianum

1'. Plants sparsely to densely pilose, strigose, strigillose, or velutinous; calyx lobes linear to triangular or lanceolate; Australia, New Zealand, and central to northern Andes of South America.

   2. Leaves densely velutinous; calyx lobes 5-6 mm long, linear; corolla ca. 15 mm long; Colombia....Leptostigma longiflorum

   2'. Leaves pilose to striglose or strigillose; calyx lobes to lanceolate, 1-3 mm long; corolla 5-12 mm long; Australia, New Zealand, central to northern Andes.  

      3. Calyx with 2 developed lobes and 2 rudimentary lobes, these remaining erect in fruit; stipules truncate with 1-3 minute setae or teeth; Australia, New Zealand.

         4. Flowers subsessile to shortly pedicellate; calyx lobes narrowly triangular, setose; corolla 8-12 mm long, on outer surface glabrous except hirsute on margins of lobes; fruit longitudinally ridged; southeastern Australia......Leptodermis reptans

         4'. Flowers sessile or subsessile; calyx lobes lanceolate, entire; corolla 5-10 mm long, on outer surface hispid in upper half; fruits smooth or weakly longitudinally ridged; New Zealand.....Leptodermis setulosum

      3'. Calyx with 4-6 developed lobes, these refexed in fruit; stipules triangular with 3-7 lobes or segments; central to northern Andes.

         5. Leaves 9-30 x 8-25 mm; stipules with 5-7 lobes; corolla with tube 4.5-10 mm long and lobes 1-2.5 mm long; fruits 5 x 3.5 mm long.....Leptodermis pilosum

         5'. Leaves 6-10 x 4-5 mm; stipules with 3-5 lobes (but see discussion of this species on its project page); corolla with tube 5-10 mm long and lobes 1-2.5 mm long; fruits 2-4 mm long.....Leptodermis weberbaueri

 
 
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