Solanum erianthum

Citation author:

D.Don

Citation:

Prodr. Fl. Nepal. 96. 1825.

Type:

Nepal. “In Valle Nepalia prope Kalmanda, 1821,” N. Wallich Herb. 2616c (lectotype, designated by Roe 1967, pg. 359: K [K neg. 7872]).

Last edited by:

Sandra Knapp (May 2014)

Written by:

Shannon Croutch

Habit:

Shrubs or small trees, 2-8 m high, forming flat-topped spreading crowns, unarmed. Trunks to 25 cm in diameter; bark of older stems gray or brown; young branches longitudinally angled and grooved, whitish to yellowish granular-tomentose, the trichomes sessile and short-stalked, echinoid and dendritic-echinoid.

Sympodial structure:

Sympodial units plurifoliate, axillary leaves absent; branching dichasial.

Leaves:

Leaves simple, the blades usually 10-25 x 3-15 cm, ca. 1.5-3 times as long as wide, ovate to ovate-elliptic, rarely obovate or orbicular, usually subcoriaceous, discolorous; adaxial surface soft velutinous-tomentose to finely scabridulous, the hairs stalked, simple, porrect-stellate and multangulate; abaxial surface whitish-tomentose, the hairs stalked, porrect-stellate and multangulate,; primary veins 9-13 pairs; base rounded, obtuse, or acute; margins entire; apex acute, acuminate or short attenuate; petioles 1-10 cm, granular-tomentose, the hairs sessile, mostly multangulate and echinoid.

Inflorescences:

Inflorescences pseudo-terminal, 5-20 cm, many times branched, with ca. 70-110 flowers, granular-tomentose, the hairs mostly sessile and short-stalked, multangulate, echinoid and dendritic-echinoid; peduncle 6.9-18.1 x 0.2-0.4 cm; rachis 0.5-2 cm; pedicels 0.2-0.6 cm in flower, articulated at the base, yellowish-tomentose, the hairs sessile and short-stalked, multangulate, echinoid and dendritic-echinoid; pedicel scars closely spaced 1.6-2.7 mm apart. Buds 4-6 mm long at anthesis, turbinoid; calyx enclosing the corolla, yellowish-tomentose, the hairs multangulate, echinoid and dendritic-echinoid; calyx lobe sutures obscured by tomentum.

Flowers:

Flowers 5-merous, all perfect. Calyx subcampanulate, 4.8-6.9 mm long, the tube 2-3.8 mm, lobed 1/2 way, the lobes 2.2-4.3 x 1.8-4.9 mm, semi-ovate to acute, coriaceous, pubescence abaxially as in bud, tomentose adaxially, the hairs multangulate. Corolla 1.1-1.8 cm in diameter, 9-11.9 mm long, included in calyx until anthesis, stellate, white, the tube 2.9-4.2 mm, the lobes 5.1-8 x 3-4.3 mm, ovate-lanceolate to ovate, yellowish-tomentose abaxially, the hairs porrect-stellate, multangulate and echinoid, sessile to long-stalked, pubescent adaxially, the hairs simple, porrect-stellate and multangulate, most densely concentrated near the apex, less densely pubescent towards the base. Stamens equal, connivent, with filaments 1-1.9 mm long, inserted on corolla tube 1-2.5 mm above base, glabrous; anthers 2.3-3.4 x 1-1.6 mm, ellipsoid, blunt-tipped, light yellow, sometimes drying brown on the abaxial surface, poricidal at the tips, the pores directed distally and somewhat adaxially, farinose around edges, lengthening to longitudinal slits with age. Ovary semi-spherical, tomentose, the hairs multangulate and echinoid, sessile and short-stalked, the apical rays of echinoid hairs very long and villous; style 4-5.2 (-6.1) x 0.2-0.3 mm, exserted from stamens, cylindrical, glabrous or sometimes sparsely stellate-pubescent; stigma capitate.

Fruits:

Fruit a fleshy berry, 0.9-1.8 cm in diameter, globose, obtuse at apex, yellow when ripe, the tomentum persistent; fruiting calyx accrescent, enveloping but not completely covering the fruit, pubescence as in flower, though becoming somewhat glabrescent near the base adaxially, the lobes 2.4-6.2 x 2.7-7.3 mm; fruiting pedicels 0.4-1.1 cm, erect.

Seeds:

Seeds numerous, 1.4-2 x 1.1-1.6 mm, lenticular to deltoid, yellowish-tan, the surface reticulate-punctate.

Chromosome number:

2n=24 (voucher Roe 91, WIS) Roe, K. E. 1967. A revision of Solanum sect. Brevantherum (Solanaceae) in North and Central America. Brittonia 19: 353-373.

Distribution:

Solanum erianthum is a common weedy species throughout most of Mexico, Central America and the West Indies except for the arid interior of northern Mexico, and is the only member of sect. Brevantherum reaching the United States. It is common in southern Florida and found in Cameron County, Texas near the Gulf of Mexico. Frequent in thickets of secondary-growth vegetation, along roadsides and fields and in other disturbed habitats, as well as in forest openings and along riverbanks.

Solanum erianthum is native to North and Central America and is apparently rare in northern South America. It is adventive in India, China, the East Indies, and Australia. It was possibly introduced to the Philippines and thence to China, and elsewhere during the Spanish Galleon trade from Mexico, which commenced in the 16th century.

Solanum erianthum occurs in many vegetation zones, from humid lowland evergreen tropics near sea level to dry Acacia-cactus thorn-scrub and, at higher altitudes (to 2000 m) in Pinus-Quercus forests. It is most common, however, below 1000 m. Individual scattered plants are most commonly seen but large thickets also occur where conditions are favorable.

Phylogeny:

Solanum erianthum belongs to the Brevantherum clade (sensu Bohs, 2005),and is a member of section Brevantherum sensu stricto.

Commentary:

Solanum erianthum is an extremely common felty white shrub, occurring in disturbed areas worldwide and could be characterised as an invasive species. The leaves are strongly foetid smelling, and the fruits are held high above the leaves. They are most likely distributed by bats. The corollas are usually white with lobes having greenish midveins but are reportedly yellow or yellowish orange on some specimens from China. Solanum erianthum is native in Central America and the Caribbean but is widely introduced and naturalised in tropical and subtropical areas around the world.

Solanum erianthum is very similar morphologically to S. hazenii (with which it occurs sympatrically in its native range) but differs from that species in its bud bases that are not markedly swollen and in its tomentose ovary (and berry). It differs from S. umbellatum, with which it is also sympatric, in its echinoid or dendritic-echinoid trichomes, S. umbellatum has porrect stellate trichomes that are often long-stalked and in general has a more floccose appearance, especially on the new growth. Solanum erianthum is one of two widely distributed and often invasive species of the Brevantherum group, the other is S. mauritianum, which differs from S. erianthum in its orbicular buds, and velutinous or lanate pubescence of long-stalked trichomes. Solanum mauritianum usually also has numerous small, axillary leaves and uniformly purple corollas or purple corollas with a broad white midvein stripe, but not always.

This species has been known traditionally but erroneously as Solanum verbascifolium L., now a rejected name (nom. rej.; Roe, 1968; see also Jarvis, 2007). Urban (1920) recorded how the name S. verbascifolium came to be misapplied shortly after its publication in 1753. Solanum erianthum is also often confused in areas outside its native distribution with S. mauritianum, the other widespread and invasive species in this group; older literature references to S. verbascifolium could refer to either of the two taxa.

References:

Bohs, L. 2005. Major clades in Solanum based on ndhF sequences. Pp. 27-49 in R. C. Keating, V. C. Hollowell, & T. B. Croat (eds.), A festschrift for William G. D’Arcy: the legacy of a taxonomist. Monographs in Systematic Botany from the Missouri Botanical Garden, Vol. 104. Missouri Botanical Garden Press, St. Louis.

Roe, K. E. 1967. A revision of Solanum sect. Brevantherum (Solanaceae) in North and Central America. Brittonia 19: 353-373.

Roe, K. E. 1968. Solanum verbascifolium L., misidentification and misapplication. Taxon 17: 176-179.

Roe, K. E. 1972. A revision of Solanum section Brevantherum (Solanaceae). Brittonia 24: 239-278.

Urban, I. 1920. Sertum Antillanum, VIII. Repert. Spec. Nov. Regni Veg. 16: 32-41.

Jarvis, C. 2007. Order out of chaos: Linnaean plant names and their types. Linnean Society of London & the Natural History Museum, London.

Common names and uses:

United States of America. Potato tree; Mullein nightshade.

Taxonomic name:

Solanum erianthum (Solanaceae)

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