Solanum muricatum [Aiton ]

Solanum muricatum

Citation author:

Aiton

Citation:

Hort. Kew, ed. 1, 1: 250. 1789.

Type:

Cultivated at the Royal Botanic Gardens, Kew introduced in 1785 by M. Thouin

Written by:

Sandra Knapp

Habit:

Upright to scandent shrub growing to 3 m tall. Stems terete, sparsely strigose with appressed antrorse simple 3-celled uniseriate bayonet (2 long cells with a smaller cell at the tip) hairs 0.5-1 mm long, and smaller papillae; new growth sparsely to densely strigose; bark of older stems greenish grey or grey-brown.

Sympodial structure:

Sympodial units plurifoliate, the leaves not geminate.

Leaves:

Leaves simple, occasionally ternate or pinnatifid on juvenile branches, very variable in size along the stems, (3.5-)5.5-13 cm long, (1.5-)1.7-4.5 cm wide, narrowly elliptic, dark green, membranous; adaxial and abaxial surfaces sparsely pubescent on veins and lamina with antrorse, simple, uniseriate 3-celled bayonet hairs 0.2-1 mm long; primary veins 8-12 pairs, impressed above; base attenuate; margins entire, if leaves pinnatifid the lobes narrowly elliptic with entire margins, interstitial leaflets absent; apex acute; petiole (2-)2.5-7 cm long, much longer on lower leaves, sparsely pubescent with simple bayonet trichomes like those of the stems and leaves.

Inflorescences:

Inflorescences 4-8 cm long, terminal or appearing leaf-opposed, unbranched or occasionally forked, with 8-20 flowers clustered near the tips; peduncle 3-6.5 cm long, sparsely strigose with simple uniseriate bayonet trichomes like those of the stems and leaves; pedicels 1-1.2 cm long, ca. 1 mm in diameter at the base, ca. 1.5 mm in diameter at the apex, erect to spreading, sparely strigose with simple uniseriate bayonet trichomes like those of the rest of the inflorescence, articulated at the base; pedicel scars irregularly spaced 1-2 mm apart in the distal part of the inflorescence. Buds ellipsoid, the corolla included in the calyx tube until just before anthesis.

Flowers:

Flowers 5-merous, all perfect. Calyx with the tube 2-4 mm long, long-conical, the lobes 2.5-3 mm long, long-triangular, sparsely pubescent with antrorse simple uniseriate 3-celled bayonet trichomes like those of the rest of the inflorescence. Corolla 1.5-2(-4) cm in diameter, rotate, white to purple, or striped with the interpetalar tissue white and the lobes purple, the lobes 0.5-1 mm long, 0.5-1 mm wide (acumens), spreading at anthesis, adaxially glabrous, abaxially sparsely strigose pubescent along the midveins with simple, uniseriate trichomes, densely papillate on the tips and margins. Stamens equal; filament tube ca. 0.5 mm long, glabrous; free portion of the filaments 0.1-1 mm long, glabrous; anthers 3.5-6 mm long, ca. 1 mm wide, ellipsoid, bright yellow; poricidal at the tips, the pores lengthening to slits with age. Ovary conical, glabrous; style 5-9 mm long, densely papillate in the lower half, with a few simple uniseriate trichomes ca. 0.1 mm long; stigma clavate, the surface minutely papillate.

Fruits:

Fruit a very variably shaped berry, from ovoid with a pointed tip to almost globose or elongate and tapering, 5-10 cm in diameter and 6-10 cm long, pale yellow with purple stripes when mature, occasionally pale purple to dark purple throughout, the mesocarp fleshy, usually pale yellow or orange, sweet-scented, the pericarp thin, glabrous; fruiting pedicels woody and pendant, ca. 2-3 mm in diameter (or larger) at the base; fruiting calyx lobes breaking off, not markedly accrescent.

Seeds:

Seeds > 100 per berry, ca. 1.5 mm long, ca. 1 mm wide, pale tan or brownish red, flattened reniform, the surfaces minutely pitted (most cultivars are parthenocarpic and do not produce seeds), the testal cells pentagonal in outline.

Chromosome number:

n = 12 (Anderson, G. J. 1975. Chromosome numbers in Solanum. In. A. Löve [ed.], IOPB chromosome number reports XLVIII. Taxon 24: 370).

Distribution:

Solanum muricatum is a plant known only from cultivation, whose origins are in the Andean region of South America (Prohens et al. 1996). It is becoming more commonly cultivated worldwide, especially in temperate regions of Asia.

Phylogeny:

Solanum muricatum is a member of section Basarthrum in the Potato clade sensu Weese and Bohs (2007). The phylogenetic position as a member of the section has been supported with molecular data (Prohens et al. 2006; Blanca et al. 2007).

Commentary:

Solanum muricatum (pepino) is a domesticate of Andean origin vegetatively propagated by stem cuttings and esteemed for its edible fruit, a berry that is juicy, scented, mild and sweet, and that can be highly variable in shape and colour. When ripe the fruits have the flavour of musk-melon or canteloupe, and when unripe like cucumber (Prohens et al. 1996). It is known only from cultivation and is mentioned in the writings of the early Spanish explorers of the Andes (Anderson 1975; Prohens et al. 1996). The pepino has been grown for thousands of years in the Andean region, and it was an important crop during the times of the Inca Empire. However, until recently, concurrent with increasing interest in international markets, the pepino has been grown largely for local consumption (IPGRI 2004). It is often grown as an annual or pluriannual crop, and in the Andes is cultivated from sea level to above 3000 m elevation. In Europe it is being developed as a greenhouse crop (Prohens and Nuez 1999; Prohens et al. 2010).

The pepino is well-represented in pre-Colombian pottery from the Paracas and Mochica cultures of coastal Peru (Prohens et al. 1996) and in offerings from the Cuzco area (Vargas 1962). Many fruit shapes were recorded by early chroniclers, and the crop’s distribution at the time of the Spanish arrival was far beyond its origins in Peru and stretched as far north as Mexico (Prohens et al. 1996). It was distributed elsewhere in cultivation following on from the Ruiz and Pavon expedition to discover the plant riches of Spanish territories in the New World (Prohens et al. 1996), from where it was introduced into Europe in the late 17th century, then reintroduced more widely in the late 19th century, including into the United States.

Prohens et al. (1996) suggest that among the reasons for neglect of the pepino as a fruit crop include its narrow temperature range for fruit set, its clonal nature leading to narrowly adapted genotypes in particular places, high sensitivity of fruit quality to environmental conditions during ripening, and the length of time needed for fruit ripening. This is being overcome, especially in Asia (pepino is very popular in China), but the pepino still lags far behind other solanaceous fruits in popularity, despite its nutritional and flavour qualities.

The 3-celled antrorse simple trichomes on vegetative parts of S. muricatum have been termed bayonet hairs and are a common feature of the Basarthrum group (Seithe and Anderson 1982); they are transparent, stiff and the cells are long as compared to other simple trichomes in Solanum. Correll (1962) distinguished the pepino by its simple leaves, but ternate or pinnatifid juvenile leaves occur on some plants (these were distinguished at the varietal level by Correll). Although sometimes attaining a vining habit like other members of the Basarthrum group, most plants of S. muricatum are shrubby in cultivation. The relationships of the pepino in the Basathrum group are not clear; karotypically it is the most distinct and most variable of all species examined (Bernardello and Anderson 1990), and it has been suggested that it arose from one of several Andean taxa (e.g., S. basendopogon, S. caripense, S. tabanoense). In the analyses of Weese and Bohs (2007) it was sister to S. fraxinifolium, the only other member of the group included; Sarkinen et al. (2013) resolved S. muricatum as the first branch in the Basathrum group.

References:

Anderson, G. J. 1975. Chromosome numbers in Solanum. In. A. Löve [ed.], IOPB chromosome number reports XLVIII. Taxon 24: 367-372.

Anderson G.J. 1975. The variation and evolution of selected species of Solanum section Basarthrum (Solanaceae). Brittonia, 27: 209-222.

Anderson, G. J. 1977. The variation and evolution of selected species of Solanum section Basarthrum (Solanaceae). II. Brittonia 29: 116-128.

Blanca, J. M., J. Prohens, G. J. Anderson, E. Zuriaga, J. Cañizares, and F. Nuez. 2007. AFLP and DNA sequence variation in an Andean domesticate, pepino (Solanum muricatum, Solanaceae): implications for evolution and domestication. American Journal of Botany 94: 1219-1229.

Correll, D. S. 1962. The potato and its wild relatives. Texas Research Foundation, Renner, TX.

Prohens, J., J. J. Ruiz and F. Nuez. 1996. The pepino (Solanum muricatum, Solancaeae): a “new” crop with a history. Economic Botany 50: 355-368.

Prohens, J. and F. Nuez. 1999. Strategies for breeding a new greenhouse crop, the pepino (Solanum muricatum Aiton). Canadian Journal of Plant Science 79: 269-275.

Prohens, J., G. J. Anderson, J. M. Blanca, J. Cañizares, E. Zuriaga, and F. Nuez. 2006. The implications of AFLP data for the systematics of the wild species of Solanum section Basarthrum. Systematic Botany 31: 208-216.

Prohens, J., A. Fita, M. Plazas and A. Rodriguez-Burruezo. 2010. Introduction and adaptation of the Andean Solanum muricatum as a new crop for the Mediterranean region. Bulletin UASVM Horticulture 67: 264-269.

Seithe, A., and G. J. Anderson. 1982. Hair morphology and the relationships of species in Solanum sect. Basarthrum. Plant Syst. and Evol. 139: 229-256.

Weese, T. L. and L. Bohs. 2007. A three-gene phylogeny of the genus Solanum (Solanaceae). Systematic Botany 32: 445-463.

Common names and uses:

pepino, pepino dulce

Conservation status:

Solanum muricatum is known only from cultivation.

Solanaceae Source

A global taxonomic resource for the nightshade family

Solanaceae

Solanum muricatum Aiton

Primary tabs

NCBI