Genlisea


Genlisea is a genus of carnivorous plants also known as corkscrew plants. The 30 or so species grow in wet terrestrial to semi-aquatic environments distributed throughout Africa and Central and South America. The plants use highly modified underground leaves to attract, trap and digest minute microfauna, particularly protozoans. Although suggested a century earlier by Charles Darwin, carnivory in the genus was not proven until 1998.
The generic name Genlisea honors the late Stéphanie Félicité Ducrest de St-Albin, comtesse de Genlis, a French writer and educator.
Several species in the genus, including G. margaretae, G. aurea, and G. tuberosa, possess the smallest known genomes of all flowering plants.

Description

Genlisea are small herbs, growing from a slender rhizome and bearing two morphologically distinct leaf types - photosynthetic foliage leaves aboveground and highly modified subterranean leaves used to trap prey. The plants lack roots, although the subterranean traps perform many of the functions normally performed by roots, such as anchorage and absorption of water and nutrients.
Several to many flowers are held by a slender, erect, and often tall inflorescence. As in other members of the bladderwort family, the corolla is fused into a bilobed tube tapering to a spur, with the lower lip of the corolla having three lobes. The calyx is five-lobed, in contrast to Utricularia's three-lobed calyx. Corolla colors are generally yellow or violet to mauve, although a few species are white or cream.
The foliage leaves grow in a around the growth point. Depending on species, these leaves are linear to spatulate in shape and 0.5–5 cm in length.
The subterranean traps are white, lacking chlorophyll or any other pigmentation. They consist of a cylindrical stalk, widening at some distance below the surface into a hollow bulb-like utricle, and continuing as a hollow cylinder some further distance. At this point the stalk into two furrowed spirals, between which the cylinder opening acts as the trap entrance. The furrows of the spiraled trap arms are lined with hairs pointing inward and toward the bifurcation. The hollow cylinder section leading from the bifurcation to the utricle is likewise lined with upward-pointing curved hairs. Some species produce two trap forms, one shorter and one longer, which probably target different prey groups.

Taxonomy

Twenty-nine species are currently recognised in the genus. Two varieties are also considered valid: G. aurea var. minor and the autonymous G. aurea var. aurea. Intraspecific determination depends almost wholly upon the inflorescence, particularly upon the indumentum.
SpeciesAuthorityYearImageDistributionSubgenusSectionGenome size
Genlisea africanaOliv.1865AfricaGenliseaAfricanae740
Genlisea angolensisR.D.Good1924AfricaGenliseaAfricanae-
Genlisea aureaA.St.-Hil.1833South AmericaGenliseaGenlisea64 & 117 - 131
Genlisea barthlottiiS.Porembski, Eb.Fisch. & Gemmel1996AfricaGenliseaAfricanae-
Genlisea exhibitionistaRivadavia & A.Fleischm.2011South AmericaTayloria-
Genlisea filiformisA.St.-Hil.1833South America, Central America, CubaGenliseaGenlisea-
Genlisea flexuosaRivadavia, A.Fleischm. & Gonella2011South AmericaTayloria--
Genlisea glabraP.Taylor1967South AmericaGenliseaGenlisea-
Genlisea glandulosissimaR.E.Fr.1916AfricaGenliseaRecurvatae154-189
Genlisea guianensisN.E.Br.1900South AmericaGenliseaGenlisea289
Genlisea hispidulaStapf1904AfricaGenliseaAfricanae1510 - 1550
Genlisea lobataFromm1989South AmericaTayloria-1200 - 1722
Genlisea margaretaeHutch.1946Africa, MadagascarGenliseaRecurvatae113 - 195
Genlisea metallicaRivadavia & A.Fleischm.2011South AmericaTayloria-1057
Genlisea nebulicolaRivadavia, Gonella & A.Fleischm.2011South AmericaTayloria--
Genlisea nigrocaulisSteyerm.1948South AmericaGenliseaGenlisea73 - 86
Genlisea oligophyllaRivadavia & A.Fleischm.2011South AmericaTayloria--
Genlisea oxycentronP.Taylor1954South America, TrinidadGenliseaGenlisea75
Genlisea pallidaFromm & P.Taylor1985AfricaGenliseaRecurvatae-
Genlisea pulchellaTutin1934South AmericaGenliseaGenlisea-
Genlisea pygmaeaA.St.-Hil.1833South AmericaGenliseaGenlisea161 - 179
Genlisea repensBenj.1847South AmericaGenliseaGenlisea77 - 86 & 142 - 150
Genlisea roraimensisN.E.Br.1901South AmericaGenliseaGenlisea-
Genlisea sanariapoanaSteyerm.1953South AmericaGenliseaGenlisea-
Genlisea stapfiiA.Chev.1912AfricaGenliseaAfricanae-
Genlisea subglabraStapf1906AfricaGenliseaAfricanae1471 - 1622
Genlisea tuberosaRivadavia, Gonella & A.Fleischm.2013South AmericaGenliseaGenlisea61
Genlisea uncinataP.Taylor & Fromm1983South AmericaTayloria-995 - 1062
Genlisea violaceaA.St.-Hil.1833South AmericaTayloria-1005 - 1609

Botanical history

The genus was discovered by Augustin François César Prouvençal de Saint-Hilaire, who in 1833 described four species: G. aurea, G. filiformis, G. pygmaea, and G. violacea.

Genome size range

The genus has a 25-fold range in genome size among its species and notably includes some of the smallest known plant genomes. For example, the genome of G. nigrocaulis is 86 Mbp while that of its close relative G. hispidula is 1550 Mbp, 18-fold larger. More than one genome size has been measured in G. aurea and G. repens, suggesting that di- and tetraploid individuals exist.