Talinella grevei Danguy

Applequist, Wendy L., 2005, A revision of the Malagasy endemic Talinella (Portulacaceae), Adansonia (3) 27 (1), pp. 47-80 : 61-62

6. Talinella grevei Danguy

Shrub or small tree with sarmentose to lianoid branches,2-4(-5) m high.Twigs straight to contorted; bark reddish brown to tan or dark brown; lenticels present or absent, usually pale, rarely dark and prominently raised; small twigs glabrous, whitepapillate or rarely white-pubescent. Leaves variable, oblong to elliptical or obovate, often irregularly shaped, 0.5-4.0(-5.0) cm long, 1.5-14.0(-22.0) mm broad, thick or succulent, often clustered on short shoots; apex variable, acute to rounded, minutely apiculate, mucronulate or emarginate, often darktipped, sometimes truncate or asymmetrical; base tapering; margins entire or laterally revolute, occasionally papillose or ciliate; midrib conspicuous beneath, sometimes papillose, secondary venation invisible; petiole and leaf blade glabrous or rarely white-papillose or pubescent. Inflorescences often numerous, lateral on short or long shoots or terminal, occasionally forming a large compound panicle; fertile portion (1-)3-6(-16) cm long; shape variable, usually narrowly paniculiform; branches frequently compressed, with dense clusters of small buds or empty bracts; at the extreme, main branches reduced to single fertile flowers with few bracts, giving a racemose appearance. Peduncle and rachis sturdy, densely white-papillate to glabrous; bracts 0.3-1.6(-2.5) mm long, pale with dark tip, rarely papillate. Gynodioecious or perhaps functionally dioecious; female flowers with antherless staminodes, ovary enlarged in bud. Pedicel (0.2-)1.0- 2.5(-5.5) mm long, rarely pubescent. Sepals 2 (very rarely 3), (1.4-)1.8-2.6(-3.4) mm long, reddish, glabrous or rarely papillate. Petals 2 or (2-)3-4, (1.8-) 2.5-5.0(-6.1) mm long, deep pink to reddish purple, obovate to oblong, if> 2 sometimes unequal; female flowers smaller and less showy, with petals usually <3 mm long. Fertile stamens c. 20, rarely more or fewer; filaments (1.0-)1.8-3.3(-3.8) mm long, the basal portion of inner whorl usually slightly flattened and short-ciliate, sometimes densely ciliate; anthers yellow, (0.40-)0.50-0.75(-1.10) mm long, broadly elliptical to oblong. Stigma branches (2-)3(-4), (0.75-)1.50-4.00(-4.30) mm long, usually with darker central streak and pale ragged edges, the apex flattened, rarely branching; style (0.0-)0.5- 1.0(-2.0) mm long. Fruit a berry, globose, (3.5-) 4.5-7 mm in diam., green, containing 2-6 seeds; seeds 1.6-2.5 mm long, broadly reniform to suborbicular or reniform, up to 1 mm thick, with no ridge or inconspicuous shallow obtuse or rounded ridge around outer edge.

Talinella grevei is a widespread species in southern Madagascar ( Fig. 2 ), and is exceptionally diverse in characters ranging from inflorescence and floral structure to leaf characters. It is the only species that has petals and sepals of vivid deep pink to red color; it is further distinguished by its leaves, which are usually <4 cm long, oblong to elliptical, thick, without visible secondary venation and of a dull, dark to grayish green color. Twig papillae, if present, are all white, whereas most papillose species have white and brown papillae; leaves and inflorescences are sometimes white-papillose as well. The inflorescences are extremely variable but as a rule are sturdy, often dense, with many maturing flowers. Small inflorescences in T. grevei are mostly lateral, often numerous, with a single main axis and short branches, whereas most species with fewflowered inflorescences have more open, slender, irregularly shaped and often terminal inflorescences. Observations made of individuals in a roadside population indicated considerable variation in leaf and inflorescence size, perhaps in response to local factors of water availability, as those in low-lying wet spots were better developed than those only a few yards away that received less water; there can be a great range of variation even within one individual.

Four subspecies of T. grevei are herein recognized, of which two are newly described. Infraspecific variation in qualitative as well as quantitative characters, ranging from petal number to floral size, leaf size and pubescence, may be as great as the variation commonly seen among closely related species of Talinella . However, although the broad pattern of interpopulational morphological variation is correlated with geographic origin and habitat, the ranges of different subspecies may be adjacent or overlapping. Useful taxonomic characters do not vary in concert, intermediate specimens are frequent, and few specimens exist of some morphologically distinctive groups. It is not clear that these groups are reproductively isolated; therefore, it is more conservative to recognize them at the subspecific level pending further study. The white-flowered T. albidiflora , for which more collections exist, is herein segregated from T. grevei .

Talinella grevei is believed to be gynodioecious, one of the few exceptions to the dioecious condition of most species of Talinella . A minority of flowering specimens are female-only, with sterile staminodes and rapidly developing ovaries, while the majority have apparently hermaphroditic flowers with well-developed stigmas and styles, often exceeding those of the female flowers in size. However, the ovaries of hermaphroditic flowers are quite small at anthesis, and specimens bearing both flowers near anthesis and developing fruit are usually identifiable as female, so it may be surmised that “hermaphrodites” are for the most part functionally male.

CONSERVATION STATUS. — Provisional IUCN

Red List Category: Least Concern (LC).

Figures

FIG. 2. — Distribution of Talinella grevei subsp. calcicola (★), subsp. grevei ($), subsp. hirsuta (▲), subsp. sarmentosa (L), and segregate species Talinella albidiflora (●).