Violaceae

Belongs within: Violineae.
Contains: Viola.

The Violaceae are a family of flowering plants including the violets (Viola) and related species. Though the herbaceous genus Viola contains the majority of species, species in other genera of Violaceae are often shrubs. Members of the Australasian genus Hymenanthera often have spinescent branchlets and their fruit is a berry. Hybanthus is a pantropical genus of erect perennials and shrubs bearing strongly zygomorphic flowers with the lowest petal much longer than the others, and capsular fruits (Harden 1990).

Not all violets are violet

Published 27 August 2007

Violaceae are a medium-sized family (about 800 or more species), about half of which belong to the single genus Viola (violets, pansies and small string instruments). Most Violaceae are herbs, but a few are woody shrubs, trees or lianes—for instance, the South American tree Leonia triandra reaches 25m in height (see here). In fact, I get the impression that, taken genus by genus, there are actually more woody genera of Violaceae than herbaceous ones, and it is only the high diversity of the mostly herbaceous Viola that skews the ratio. Phylogenetically Violaceae are members of the rosid order Malpighiales that I’ve had cause to mention before as containing the gigantic-flowered holoparasite Rafflesia.

Violaceae don’t appear to include anything as remarkable as Rafflesia (at least as far as I know), but they are certainly not devoid of interest. Many species of Viola produce cleistogamous flowers, i. e. the flowers never open and fertilise themselves. Often (as in Viola pubescens) both cleistogamous and open flowers are produced (Culley & Wolfe, 2001), thus achieving the best of both options—the greater genetic variability obtained through outcrossing, as opposed to the more guaranteed success in setting seed of cleistogamy.

Also worth a mention are the ten or so species of Viola endemic to Hawaii, which are unique among the genus in their combination of woody stems (present in a few other species) and flowers borne in inflorescences (as opposed to singly in all other Viola). These distinctive features have lead to the suggestion that the Hawaiian species are quite basal in the genus (possibly relicts) and that they are related to basal South American Viola species that also have woody stems. However, a molecular study by Ballard & Sytsma (2000) indicates that, far from being an ancient group, the Hawaiian violets represent a single quite recent colonisation, not from South America, but from the Arctic! The sister taxon of the Hawaiian violets is the herbaceous Viola langsdorffii, found in the American Arctic and Japan. As circumstantial support for this result, Ballard and Sytsma pointed out the large numbers of migratory birds passing Hawaii from their breeding grounds in the Arctic, and that at least two Hawaiian birds appear to have recent Arctic origins—the goose Branta sandvicensis (from B. canadensis and the duck Anas wyvilliana (from A. platyrhynchos).

Systematics of Violaceae

Characters (from Harden 1990): Herbs and shrubs. Leaves alternate, simple; stipules usually present. Inflorescence a raceme or cyme or flowers solitary. Flowers zygomorphic, usually strongly so, mostly bisexual. Sepals 5, imbricate, persistent. Petals 5, imbricate, free, the lowest often largest and spurred. Stamens 5, hypogynous, alternate with petals; filaments very short; anthers free or fused around ovary, the connective usually produced into an appendage. Ovary superior, 1-locular, usually with 3 parietal placentas; style simple, stigma terminal. Fruit a capsule or berry; seeds 2–many.

<==Violaceae [Violarieae]
    |--Fusispermum [Fusispermoideae]XR12
    `--+--RinoreaXR12
       `--+--+--Leonia [Leonioideae]XR12
          |  |    `--L. glycycarpaWM09
          |  `--HybanthusXR12
          |       |--H. aurantiacusLK14
          |       |--H. concolorBS00
          |       |--H. debilissimusGK00
          |       |--H. enneaspermusLK14
          |       |    |--H. e. ssp. enneaspermusH90
          |       |    `--H. e. ssp. stellarioidesH90
          |       |--H. floribundusGK00
          |       |--H. monopetalusH90
          |       `--H. vernoniiH87
          |            |--H. v. ssp. vernoniiH90
          |            `--H. v. ssp. scaberH90
          `--+--ViolaXR12
             `--Hymenanthera Br. 1818XR12, A61
                  |--H. alpina (Kirk) Oliver 1944A61 [=H. dentata var. alpina Kirk 1899A61, Melicytus alpinusD95]
                  |--H. angustifolia Br. ex DC. 1824 [=H. dentata var. angustifolia (Br.) Benth. 1863]A61
                  |--H. banksiiB08
                  |--H. chathamica (Muell.) Kirk 1896 [=H. latifolia var. chathamica Muell. 1864]A61
                  |--H. crassifolia Hook. f. 1852A61
                  |--H. dentataA61
                  |--H. lanceolatusME70
                  |    |--H. l. var. lanceolatusME70
                  |    `--H. l. var. latiorME70
                  |--H. latifoliaC06
                  |--H. novae-zelandiae (Cunn.) Hemsl. 1908 (see below for synonymy)A61
                  `--H. obovata Kirk 1895A61

Violaceae incertae sedis:
  Melicytus Forster & Forster 1776A61
    |--M. flexuosusD95
    |--M. lanceolatus Hook. f. 1776A61
    |    |--M. l. var. lanceolatusA61
    |    `--M. l. var. latior Simpson & Thomson 1942A61
    |--M. latifoliusD95
    |--M. macrophyllus Cunn. 1840A61
    |--M. micranthus Hook. f. 1852 [=Elaeodendron micranthum Hook. f. 1844]A61
    |    |--M. m. var. micranthusA61
    |    |--M. m. var. longiusculus Cheesem. 1906A61
    |    `--M. m. var. microphyllus (Col.) Cheesem. 1906 [=M. microphyllus Col. 1887]A61
    |--M. novae-zelandiaeLM98
    `--M. ramiflorus Forster & Forster 1776A61
  Anchietea salutarisPB03
  Noisettia orchidifloraBS00
  Ionidium filiformeC06
  Clelandia Black 1932KC01
  Medusula Pers. 1807KC01
  Cubelium concolorMB22
  SchweiggeriaMB22
  AfrohybanthusMB22
  AgateaMB22
  PigeaMB22
  Pombalia parviflora [=Viola parviflora]MB22

Nomen nudum: Melicytus collina Colenso 1845C45

Hymenanthera novae-zelandiae (Cunn.) Hemsl. 1908 [=Scaevola novae-zelandiae Cunn. 1839; incl. H. latifolia var. tasmanica Kirk 1871]^A61

*Type species of generic name indicated

References

[A61] Allan, H. H. 1961. Flora of New Zealand vol. 1. Indigenous Tracheophyta: Psilopsida, Lycopsida, Filicopsida, Gymnospermae, Dicotyledones. R. E. Owen, Government Printer: Wellington (New Zealand).

[BS00] Ballard, H. E., Jr & K. J. Systsma. 2000. Evolution and biogeography of the woody Hawaiian violets (Viola, Violaceae): Arctic origins, herbaceous ancestry and bird dispersal. Evolution 54 (5): 1521–1532.

[B08] Brittlebank, C. C. 1908. The life-history of Loranthus exocarpi Behr. Proceedings of the Linnean Society of New South Wales 33: 650–656, pls 15–20.

[C06] Cheeseman, T. F. 1906. Manual of the New Zealand Flora. John Mackay, Government Printer: Wellington.

[C45] Colenso, W. 1845. Memoranda of an excursion, made in the Northern Island of New Zealand, in the summer of 1841–2; intended as a contribution towards the natural productions of the New Zealand groupe: with particular reference to their botany (concluded). Tasmanian Journal of Natural Science 2: 241–308.

Culley, T. M., & A. D. Wolfe. 2001. Population genetic structure of the cleistogamous plant species Viola pubescens Aiton (Violaceae), as indicated by allozyme and ISSR molecular markers. Heredity 86 (5): 545–556.

[D95] Dawson, M. I. 1995. Contributions to a chromosome atlas of the New Zealand flora. 33. Miscellaneous species. New Zealand Journal of Botany 33: 477–487.

[GK00] Gibson, N., & G. J. Keighery. 2000. Flora and vegetation of the Byenup-Muir reserve system, south-west Western Australia. CALMScience 3 (3): 323–402.

[H90] Harden, G. J. (ed.) 1990. Flora of New South Wales vol. 1. New South Wales University Press.

[H87] Haviland, E. 1887. Flowering seasons of Australian plants. No. I—List of plants indigenous in the neighbourhood of Sydney, flowering during July. Proceedings of the Linnean Society of New South Wales, series 2, 1 (4): 1049–1051.

[KC01] Kirk, P. M., P. F. Cannon, J. C. David & J. A. Stalpers. 2001. Ainsworth & Bisby’s Dictionary of the Fungi 9^th ed. CAB International: Wallingford (UK).

[LM98] Lange, P. J. de, & B. G. Murray. 1998. Senecio repangae (Asteraceae): a new endemic species from the north-eastern North Island, New Zealand. New Zealand Journal of Botany 36: 509–519.

[LK14] Lyons, M. N., G. J. Keighery, L. A. Gibson & T. Handasyde. 2014. Flora and vegetation communities of selected islands off the Kimberley coast of Western Australia. Records of the Western Australian Museum Supplement 81: 205–244.

[MB22] Marcussen, T., H. E. Ballard, J. Danihelka, A. R. Flores, M. V. Nicola & J. M. Watson. 2022. A revised phylogenetic classification for Viola (Violaceae). Plants 11: 2224.

[ME70] Moore, L. B., & E. Edgar. 1970. Flora of New Zealand vol. 2. Indigenous Tracheophyta: Monocotyledones except Gramineae. A. R. Shearer, Government Printer: Wellington (New Zealand).

[PB03] Poinar, G. O., Jr & A. E. Brown. 2003. A non-gilled hymenomycete in Cretaceous amber. Mycological Research 107 (6): 763–768.

[WM09] Wang, H., M. J. Moore, P. S. Soltis, C. D. Bell, S. F. Brockington, R. Alexandre, C. C. Davis, M. Latvis, S. R. Manchester & D. E. Soltis. 2009. Rosid radiation and the rapid rise of angiosperm-dominated forests. Proceedings of the National Academy of Sciences of the USA 106 (10): 3853–3858.

[XR12] Xi, Z., B. R. Ruhfel, H. Schaefer, A. M. Amorim, M. Sugumaran, K. J. Wurdack, P. K. Endress, M. L. Matthews, P. F. Stevens, S. Mathews & C. C. Davis. 2012. Phylogenomics and a posteriori data partitioning resolve the Cretaceous angiosperm radiation Malpighiales. Proceedings of the National Academy of Sciences of the USA 109 (43): 17519–17524.