Neotropical Molluginaceae

Description

Herbs, rarely woody plants, often creeping and well branched. Leaves alternate, opposite or verticillate, with or without stipules, sessile to shortly petiolate, sometimes linear, venation inconspicuous, blades entire, herbaceous to slightly fleshy. Inflorescences in small cymes to axillary fascicles, flowers sometimes solitary. Flowers hermaphrodite, symmetry radial, hypogynous, relatively small, white, cream or greenish, calyx (4-)5-merous, lobes free to fused at base, corolla absent, sometimes replaced by staminodes; stamens (2-)4-5, rarely more, free or united at base, anthers dehiscing longitudinally; nectar disk present, surrounding the gynoecium; ovary superior, 2-5-locular, axile placentation, (1-)many ovulate, ovules pendulous. Fruit capsular or achene, seeds black or brown with shiny coat, embryo curved around perisperm, endosperm absent.

Notes on delimitation

• Together with the Aizoaceae, Cactaceae, Portulacaceae and Stegnospermataceae, the Molluginaceae is currently placed within order Caryophyllales (APGII, 2003). However, it lacks the betalain pigments and has rather modest, small flowers.

Distribution in the Neotropics

• Out of its 10-13 genera and approx. 120 species, this family is represented in the Neotropics by 3 genera and 3 species:  Mollugo L., Glinus L. and Glischrothamnus Pilg.
• All are found in dry, open Neotropical environments. Mollugo verticillata L. and Glinus radiatus (Ruiz & Pav.) Rohrb. are weedy and commonly found in disturbed habitats.
• Mollugo L. - throughout the Neotropics, only one species, M. verticillata.
• Glinus L. - a single weedy, widespread species, G. radiatus.
• Glischrothamnus Pilg. - a narrow endemic, monotypic genus from the Brazilian drylands, G. ulei Pilg.

Distinguishing characters (always present)

• Generally herbaceous plants with flowers lacking corolla.
• Superior ovary.
• Relatively small flowers.

Other important characters

• Leaves often opposite.
• Stamens usually 5.
• Ovary pluri-ovulate.
• Seed with shiny seed -coat.

Key differences from similar families

• May be confused with Galium L. and other herbaceous Rubiaceae because of its general habit, but has superior ovary and free petals (Rubiaceae has inferior ovary and gamopetalous corolla).
• It can be confused with Aizoaceae and Portulacaceae, but is less succulent and has smaller, less colourful flowers than those.

Number of genera

• This family is represented in the Neotropics by 3 genera and 3 species:  Mollugo L., Glinus L., and Glischrothamnus Pilg.,

Useful tips for generic identification

Key to genera of Neotropical Molluginaceae

1. Woody plants ... Glischrothamnus ulei
1. Herbaceous plants ... 2

2. Leaves narrow, linear to linear lanceolate... Mollugo verticillata
2. Leaves spathulate to obovate... Glinus radiatus

Notable genera and distinguishing features

See above.

Status

See above.

General notes

• Molluginaceae is more diverse in Africa, and some species of Mollugo are used as herbs in cooking.

Important literature

APG II, 2003. An update of the Angiosperm Phylogeny group classification for the orders and families of flowering plants: APG II. Botanical Journal of the Linnean Society 141(4): 399-436.

Souza, V.C. & Lorenzi, H. 2005. Botânica Sistemática: guia ilustrativo para identificação das famílias de Angiospermas da flora brasileira, baseado em APG II. Nova Odessa, Brazil: Instituto Plantarum.

How to cite

Zappi, D. (2010). Neotropical Molluginaceae. In: Milliken, W., Klitgård, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://www.kew.org/science/tropamerica/neotropikey/families/Molluginaceae.htm.