Solanum macrotonum Bitter, Repert. Spec. Nov. Regni Veg. 11: 222. 1912

Knapp, Sandra, Barboza, Gloria E., Bohs, Lynn & Saerkinen, Tiina, 2019, A revision of the Morelloid Clade of Solanum L. (Solanaceae) in North and Central America and the Caribbean, PhytoKeys 123, pp. 1-144 : 60-65

8. Solanum macrotonum Bitter, Repert. Spec. Nov. Regni Veg. 11: 222. 1912 Figures 24 , 25

Solanum megalophyllum Bitter, Repert. Spec. Nov. Regni Veg. 11: 202. 1912. Type. Cultivated in England (?) ex Herb. A.B. Lambert "Villa Caracas cultum in hort. Boyton, Ph. Woodford", Anon. s.n. (lectotype, designated here: W [acc. # 1889-0291427]; isolectotype: W [acc. # 1889-0291426, F neg. 33091]).

Solanum diodontum Bitter, Repert. Spec. Nov. Regni Veg. 12: 552. 1913. Type. Panama. Chiriqui: around El Potrero Camp, 2800-3000 m, 10-13 Mar 1911, H. Pittier 3104 (holotype: US [US00027551, acc. # 677494]; isotype: GH [GH00077485], NY [NY00138980], US [US00027550, acc. # 1405957]).

Solanum leonii Heiser, Ceiba 4: 298. 1955. Type. Costa Rica. Cartago: near Robert, Irazú [protologue -wooded ravine 1/2 mile below Finca Robert], 8,500 ft., 4 Oct 1953, C.B. Heiser 3597 (holotype [two sheets]: IND [sheet 1, IND-0136009, acc. # 95138; sheet 2, IND-00136010, acc. # 95137]; isotype: F [v0073111F, acc. # 143245, F neg. 49431]).

Solanum paredesii Heiser, Ci. & Naturaleza [Quito] 6: 55. 1963. Type. Ecuador. Pichincha: [ Cantón Quito] laderas al norte de los terrenos de la Universidad Central, Ciudad Universitaria Quito, 24 May 1962, C.B. Heiser 5001 (holotype: IND [IND-0136006, acc. # 106787]; isotype: Q [n.v.]).

Type.

Venezuela. Aragua: Colonia Tovar, Sep 1847, J.W.K. Moritz 1643 (holotype: B, destroyed; lectotype, designated by D’Arcy 1974a, pg. 737: P [P00336967]; isolectotypes: B [destroyed, F. neg. 2669], BM [BM000617678], F [v0073325F, acc. # 612111], HBG [HBG-511459], K [K000585559]).

Description.

Perennial herb, woody at the base, 0.7-2 m tall, perhaps occasionally annual or only persisting for a few years. Stems terete or angled with spinescent processes, often described as “viney”, arching and scrambling over other vegetation, often drying blackish grey; young stems densely pubescent with somewhat antrorse, simple uniseriate eglandular trichomes 0.5-1 mm long, the trichomes drying white, soon glabrescent; new growth densely white pubescent like the young stems, glabrescent; bark of older stems green to greenish brown. Sympodial units difoliate or unifoliate, the leaves not geminate. Leaves simple, occasionally with a few dentate teeth near the base, (2)4-10(12) cm long, (0.8)1.8-4.5(5.5) cm wide, elliptic to narrowly obovate, sometimes thick (described as succulent), but more often membranous; adaxial surfaces sparsely pubescent with simple 3-4-celled uniseriate trichomes or almost glabrous, the trichomes denser on veins and midrib; abaxial surfaces sparsely pubescent to glabrous like the adaxial surfaces, but the trichomes denser along the veins; principal veins 5-7 pairs, drying paler abaxially; base abruptly attenuate along the petiole; margins entire to sparsely toothed near the base; apex acute to narrowly acute; petiole 0.5-2.5 cm, sparsely pubescent with antrorse simple uniseriate trichomes like those of the stems and leaves. Inflorescences internodal or very occasionally leaf-opposed, 0.7-4 cm long, unbranched, with 2-3(7) flowers clustered in the distal part of the rhachis (sub-umbelliform), sparsely pubescent with simple uniseriate trichomes like those of the stems and leaves; peduncle 0.5-4 cm long; pedicels 1-1.3 cm long, ca. 0.5 mm in diameter at the base, ca. 1 mm in diameter at the apex, tapering gradually and appearing relatively stout, often described as reddish purple or purple, spreading at anthesis, sparsely pubescent or glabrous, articulated at the base; pedicel scars tightly packed in the distal portion of the inflorescence, less than 0.5 mm apart or occasionally the lowermost scar to 2 mm apart. Buds broadly ellipsoid to subglobose, the corolla long-exserted from the calyx tube before anthesis. Flowers 5-merous, perfect. Calyx tube 1-1.5 mm long, conical, the lobes 0.5-0.8(1) mm long, 0.5-1 mm wide, broadly deltate with acute apices, sparsely pubescent with simple uniseriate trichomes like those of the pedicel or almost glabrous. Corolla 10-20 mm in diameter, white to lilac or tinged with lilac, the central portion yellowish green, stellate, lobed 1/2 to 2/3 of the way to the base, the lobes 4-6 mm long, 1.5-3 mm wide, triangular, reflexed or spreading at anthesis. Stamens equal; filament tube minute and barely visible, the free portion of the filaments 1-2 mm long, pubescent with tangled simple uniseriate trichomes adaxially; anthers (2.7)3-4 mm long, 1-1.5 mm wide, ellipsoid, bright yellow, the surfaces smooth, poricidal at the tips, the pores elongating to slits with age. Ovary glabrous; style 5-6 mm long, densely pubescent with tangled simple uniseriate trichomes in the basal half where included in the anther cone, exserted from the anther cone; stigma capitate or minutely capitate, bright green, the surface densely papillate. Fruit a globose berry, 0.8-1 cm in diameter, green turning to black when ripe, or occasionally green when ripe (Nee & Whalen 16839), opaque, the pericarp thin, more or less shiny but not brilliantly so; fruiting pedicels 15-17 mm long, tapering from a base 0.7-1 mm in diameter to an apex 1.5-2 cm in diameter, somewhat woody, strongly deflexed(very occasionally appearing spreading due to herbarium specimen preparation), dropping with mature fruits or occasionally remaining on the inflorescence rhachis; fruiting calyx not accrescent, the tube 1-1.5(2) cm long, appressed to the berry, the lobes 0.5-1 mm long, appressed or spreading at the tips. Seeds (10)30-50 per berry, 1.2-1.5 mm long, 0.8-1 mm wide, tear-drop shaped, tan to reddish brown, the surfaces minutely pitted, the testal cells pentagonal, more elongate and rectangular near the hilum. Stone cells (2)4-5(6) per berry, 0.5-0.7 mm in diameter. Chromosome number: 2n =2 × =24 ( Heiser 1955, as S. leonii ), 2n =6 × =72 ( Heiser 1963, as. S. paredesii ).

Distribution.

(Figure 26 ) Solanum macrotonum occurs from Guatemala to northern South America and in the Antilles on the islands of Hispaniola and Jamaica.

Ecology.

Solanum macrotonum is a plant of open areas in cloud forests and premontane and montane forests, occurring in treefall gaps and along roads and other disturbances, from (200-)1,000 to 3,400 m elevation.

Common names.

Costa Rica. Hierba (yerba) buena ( Bohs 2015).

Uses.

None recorded.

Preliminary conservation status ( IUCN 2017).

Least Concern (LC). Solanum macrotonum is widespread and weedy in Mexico, Central America and in the Caribbean; it also occurs in northern South America. For EOO see Table 6 .

Discussion.

Solanum macrotonum is broadly sympatric with S. nigrescens across its entire range, and in Mexico and northern Central America with S. douglasii . It is similar to them in having usually 4 to 5 stone cells per berry and black fruits that are more or less shiny. It can be distinguished from S. nigrescens in having longer anthers (to 4 mm rather than to 2.5 mm) and in having more robust, longer fruiting pedicels that are strongly deflexed. It differs from S. douglasii in having strictly ellipsoid anthers (versus the slightly tapering anthers of S. douglasii ) on longer filaments, and similarly in the strongly deflexed fruiting pedicels. Many annotations in herbaria have been done based on elevation (see comments in Bohs 2015) so care must be taken with these determinations. Measurement of anthers is the best way to determine identifications unambiguously. In general, S. macrotonum does occupy slightly higher elevations than does S. nigrescens , and appears to be confined to cloud forests, but S. nigrescens has a wide elevation range and ecological tolerance.

Solanum macrotonum is one of few morelloids with differing chromosome counts across its range. D’Arcy (1974a) reported a chromosome number of “n=36” for S. macrotonum as a personal communication from J.M. Edmonds; the chromosome count in Edmonds (1972) is not new, and we presume it is a reference to the count ( “número de cromosomas - 36"; Heiser 1963) given in the protologue of S. paredesii , which Edmonds (1972) placed in tentative synonymy with S. macrotonum . Some other chromosome vouchers of S. macrotonum at IND, however (e.g., Heiser 4854) are noted as having “n=24” on the label; Heiser (1963) did not cite these in the description of S. paredesii . Chromosome counts for S. leonii , here treated in synonymy with S. macrotonum , indicate it is diploid, with n=12 ( Heiser 1955). Chromosome number variation within a species is known in Solanum (e.g., in the potatoes, see Spooner et al. 2014), and sometimes occurs sporadically at the edges of species ranges. It will be important to assess this across the range of S. macrotonum , because we cannot find any morphological characteristic that distinguishes vouchers with different chromosome counts.

Bitter (1912b) cited a single specimen from B in the protologue of S. macrotonum that is no longer extant. The sheet at P (P00336967) that has a label with all of the details cited in the protologue was chosen by D’Arcy (1974a) as the lectotype of S. macrotonum .

Solanum megalophyllum was described from cultivated specimens from the herbarium of Aylmer B. Lambert seen by Bitter (1913) in the herbarium in Vienna. Of the two specimens that are clearly duplicates of this collection, we have selected that with the more complete annotation in Bitter’s hand as the lectotype (W-1889-0291427).

Heiser (1955, 1963) described both S. leonii and S. paredesii citing “IND” as type. Heiser 5001 (type of S. paredesii ) is only represented by a single sheet, but there are two sheets of Heiser 3597, the type of S. leonii , labelled "sheet 1" and "sheet 2". We interpret this as a two-sheet holotype (see Turland et al. 2018, Art. 8, Ex. 7). Sheet 2 (IND-0136010) is better material with more leaves and flowers.

It is possible that S. frutescens A.Braun & C.D. Bouché is an older name for this taxon; that name has never been used, however, and it has been proposed for suppression (see Knapp et al. 2018; Doubtful Species).

Specimens examined.

See Suppl. materials 1 and 3.

Figures

Figure 24. Solanum macrotonum Bitter. A Reproductive stem B detail of inflorescence C detail of infructescence (A-C Moritz 1643, K 000585559). Scale bar in A: 1 cm.

Figure 25. Solanum macrotonum Bitter. A Habit B flowering branch C inflorescence with flowers at full anthesis D mature fruits (all based on Ezedin & Saerkinen 48). Photos by T. Saerkinen.

Figure 26. Distribution of Solanum macrotonum Bitter (points in northern South America included to show continuous distribution).