Neotropical Violaceae

Description

Herbs, subshrubs, shrubs, treelets or trees, less frequently lianas. Leaves alternate or less frequently opposite or pseudo-whorled, entire, serrate (the teeth bearing a terminal gland) or rarely pinnatifid or lobed; stipules present, persistent or deciduous. Inflorescences of fascicles, simple or compound cymes, (pseudo-) racemes, or flowers solitary, axillary. Flowers actinomorphic to strongly zygomorphic, bisexual or rarely unisexual, hypogynous; pedicels often articulated, bracteoles often present; aestivation usually apotact or less frequently quincuncial or convolute; sepals 5, free, equal or slightly unequal, rarely strongly unequal, persistent; petals 5, free, equal or strongly unequal in zygomorphic flowers, the lowest petal being usually bigger and gibbose or spurred; stamens 5 or rarely 3, free or the filaments fused, anthers usually with a dorsal membranous connective appendage, the filaments usually with nectar glands (in zygomorphic flowers the large nectaries are born on the filaments of the 2 dorsal stamens and are enclosed in the lowest petal's sac or spur); ovary 3-carpellate or rarely 2-4-carpellate, ovules 1-many with parietal placentation, style straight, curved or sigmoid. Fruit usually a leathery capsule, less frequently a woody or papery, bladder-like capsule, rarely a "berry" or nut; seeds (sub-)globose or less frequently strongly flattened and winged, discoid or irregularly angled, sometimes arillate, glabrous or less frequently pubescent.

Distribution in the Neotropics

• Amphirrhox Spreng. - S Central America, N South America and E coast of  South America.
• Anchietea A.St.-Hil. - Widespread in South America.
• Corynostylis Mart. Gloeospermum Triana & Planch. - Central America, N South America.
• Fusispermum Cuatrec. - S Central America, N South America.
• Hekkingia H.E.Ballard & Munzinger - French Guiana, N Brazil (Roraima).
• Hybanthopsis Paula-Souza - endemic to Bahia state (Brazil).
• Hybanthus Jacq. - Widespread.
• Leonia Ruiz & Pav. - N South America.
• Mayanaea Lundell - Guatemala.
• Noisettia Kunth - N South America and E coast of South America.
• Orthion Standl. & Steyerm. - Central America.
• Paypayrola Aubl. - S Central America, N South America.
• Rinorea Aubl. - Central America, N South America and E coast of South America.
• Rinoreocarpus Ducke - N South America.
• Schweiggeria Spreng. - E Brazil.
• Viola L. - Widespread (mainly Central America and W South America).

Other important characters

• Ovary superior, 3-carpellate with parietal placentation.
• Stipules present (although sometimes deciduous).
• Glands present at the tip of teeth on serrate leaves.
• Anthers provided with membranous connective appendages.
• Filaments provided with nectar glands.

Number of genera

17 genera:

• Amphirrhox  
• Anchietea 
• Corynostylis
• Fusispermum
• Gloeospermum  
• Hekkingia
• Hybanthopsis
• Hybanthus
• Leonia
• Mayanaea
• Noisettia
• Orthion
• Paypayrola 
• Rinorea
• Rinoreocarpus
• Schweiggeria
• Viola

Notable genera and distinguishing features

• Lianescent habit and strongly flattened seeds in Anchietea, Corynostylis and Hybanthopsis.
• Pappery, bladder-like capsules in Anchietea and Hybanthopsis.
• Capsules opening by a single londitudinal slit in Hybanthopsis.
• Auriculate sepals and pedicels not articulated in Viola.
• Sepals strongly unequal in Schweiggeria.
• Aestivation of petals convolute in Fusispermum.

Status

• All genera are endemic to the Neotropical region, except for Hybanthus, Rinorea and Viola.

Important literature

Eichler, A.W. 1871. Violaceae. In: Martius, K.F.P & Eichler, A.W. (eds.) Flora Brasiliensis. Monachii, Typographia Regia. 13 (1): 345-396.

Hekking, W. H. A. 1984. Studies on neotropical Violaceae: The genus Fusispermum. Proc. Kon. Ned. Akad. Wetensch., C 87(2): 121-130.

Hekking, W.H.A. 1988. Violaceae (Rinorea and Rioneocarpus). In: Flora Neotropica: 46 (1). The New York Botanical Garden. New York. 207p.

Morton, C.V. 1944. The genus Hybanthus in continental North America. Contr. US. Natl. Herb. 29: 74-82.

Munzinger, J.K & Ballard, H.E. 2003. Hekkingia (Violaceae), a New Arborescent Violet Genus from French Guiana, with a Key to Genera in the Family. Syst. Bot. 28 (2): 345-351.

Paula-Souza, J. & Souza, V.C. 2003a. Hybanthopsis, a new genus of Violaceae from Eastern Brazil. Brittonia. New York, U.S.A. 55 (2): 206 - 210.

Robyns, A. 1957. In: Woodson, R.E. & Schery, R.W. Flora of Panama. Ann. Missouri Bot. Gard. 54: 65-84.

Schulze, G.K. 1936. Morphologisch-systematische Studien über die Gattung Hybanthus mit besonderer Berücksichtigung der südamerikanischen Arten. Bot. Jahrb. Syst. 67: 437-492.

Smith, L.B. & Fernandéz-Pérez, A. 1954. Revisio Violacearum Colombiae. Caldasia 6 (28): 83-181.

Sparre, B. 1950. Estudios sobre las Violaceas Argentinas. Lilloa 23: 515-574.

Standley, P.C. & Williams, L.O. 1961. Flora of Guatemala 8. Fieldiana, Bot. 24, 7 (1): 70-82.

Okuoka, T. 2008. Molecular phylogenetic analysis of Violaceae (Malpighiales) based on plastid and nuclear DNA sequences. J.Plant Res. 121: 253-260.

How to cite

Paula-Souza, J. & Ballard Jr, H.E. (2009). Neotropical Violaceae. 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/Violaceae.htm.