Physalis L.
Physalis is a taxonomically difficult genus of ca. 75 species (although many more have been described). Most species are native in the neotropics. One, Physalis alkekengi var. alkekengi, is usually claimed as a very rare (now extinct) and local native in Belgium but this is rather questionable. Some species are cultivated as ornamentals (P. alkekengi) or for their edible fruits (several species but usually on a small scale and probably not in Belgium).
The generic limits of Physalis are no longer unequivocal as a result of recent molecular studies (Whitson 2005). Physalis alkekengi, the only Old World member of the genus, is an anomalous species and is perhaps better segregated (as Alkekengi officinarum Moench). However, since it is the type of the genus a new type species needs to be designated, Physalis pubescens (Whitson 2011). Pending additional studies, Physalis is here maintained in its traditional sense.
1. Corolla white or cream, rotate. Fruiting calyx orange or red at maturity. Rhizomatous perennial === 1. Physalis alkekengi
1. Corolla yellowish, often with brownish or purplish spots at throat, campanulate. Mature fruiting calyx green. Annual or perennial === 2
2. Stem densely pubescent (villous to sericeous), hairs multicellular. Corolla always with dark spots in throat === 3
2. Stem subglabrous (younger parts often with scattered, simple hairs). Corolla with or without dark spots at throat === 5
3. Corolla 15-25 mm across. Anthers 3-4 mm long. Fruiting calyx 30-50 mm wide. Leaves rounded to cordate at base, acuminate at apex, usually coarsely and evenly toothed === 6. P. peruviana
3. Corolla 7-15 mm across. Anthers 1-2 mm long. Fruiting calyx 15-30 mm wide. Leaves truncate, often oblique at base, acute at apex, usually entire or unevenly toothed === 4
4. Leaves with scattered orange spots when dry (some leaves occasionally entirely orange), very oblique at base. Corolla 7-10 mm across. Anthers yellowish. Plant odourless === 3. P. grisea
4. Leaves uniformly green when dry, not or only slightly oblique at base. Corolla 9-15 mm across. Anthers bluish. Plant with strong odour === 8. P. pubescens
5. Perennial. Flowering calyx (5-)7-12(-15) mm long === 5. P. longifolia
5. Annual. Flowering calyx 3-5 mm (or up to 10 mm long in P. philadelphica) === 6
6. Throat of corolla unspotted or with faint dark spots. Fruiting calyx angular. Peduncle 5-10 mm at anthesis, much elongating at fruiting (up to 40 mm long) === 2. P. angulata
6. Throat of corolla with distinct dark spots. Fruiting calyx terete. Peduncle up to 5 mm at anthesis, slightly elongating to ca. 10(-15) mm at fruiting === 7
7. Anthers ca. 2 mm long, not coiled after dehiscence. Corolla 5-10 mm across === 4. P. ixocarpa
7. Anthers 3-5 mm, strongly coiled after dehiscence. Corolla 10-30 mm across === 7. P. philadelphica
Additional aliens: Physalis cinerascens (Dun.) Hitchc. (N-Am., wool alien) and P. minima L. (syn.: P. lagascae Roem. et Schult., P. micrantha Link) (trop., wool alien).
Literature:
Axelius B. (1991) Odlade arter av släktet Physalis. Svensk Bot. Tidskr. 85: 413-416.
Bean A.R. (2006) Physalis (Solanaceae) in Australia - nomenclature and identification. Austr. Syst. Bot. Soc. Newsletter 127: 6-9.
Grenfell A.L. (1983) Aliens and adventives. Adventive News 26. More on Solanaceae in Britain. BSBI News 35: 12-14.
Hawkes J.G. (1972) Physalis. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 3. Cambridge University Press, Cambridge: 196.
Sell P. & Murrell G. (2009) Flora of Great Britain and Ireland. Vol. 3 Mimosaceae – Lentibulariaceae. Cambridge University Press, Cambridge: XXVIII + 595 p.
Slavík B. (2000) Solanaceae. In: Slavík B. (ed.), Kvĕtena České Republiky, vol. 6. Academia, Praha: 245-289.
Sullivan J.R. (2004) The genus Physalis (Solanaceae) in the southeastern United States. Rhodora 106: 305-326.
Van Ooststroom S.J. & Reichgelt Th.J. (1962) De in Nederland adventieve en gekweekte Physalis-soorten. Gorteria 1(7): 65-71.
Van Ooststroom S.J. & Reichgelt Th.J. (1966) Solanaceae-Orobanchaceae. In: van Ooststroom S.J. & Van der Veen R. a.o. (eds.), Flora Neerlandica, vol. 4(2). KNBV, Amsterdam: 65 p.
Ward D.B. (2008) Keys to the flora of Florida: 19, Physalis (Solanaceae). Phytologia 90(2): 198-207.
Waterfall U.T. (1958) A taxonomic study of the genus Physalis in North America north of Mexico. Rhodora 60: 107-114, 128-142, 152-173.
Waterfall U.T. (1967) Physalis in Mexico, Central America and the West Indies. Rhodora 69: 82-120, 202-239, 319-329.
Whitson M. (2005) Untangling Physalis (Solanaceae) from the Physaloides: a two-gene phylogeny of the Physalinae. Syst. Bot. 30(1): 216-230.
Whitson M. (2011) 2016: Proposal to conserve the name Physalis (Solanaceae) with a conserved type. Taxon 60: 608–609.