Hydrocotyle

Water pennywort Hydrocotyle vulgaris, from Robert Paul Hudson.

Belongs within: Araliaceae.

Hydrocotyle, the water pennyworts, is a genus of aquatic and semi-aquatic creeping plants. Some species are cultivated in aquaria but they are also known in some areas as invasive weeds.

Characters (from She, Watson & Cannon): Herbs, perennial. Stem slender, creeping or decumbent, rooting at the nodes. Leaves petiolate; petioles not sheathing; stipules present, entire or parted to base, membranous; blade cordate, orbicular, or reniform. Inflorescence a simple umbel; umbels sometimes densely capitate; peduncles axillary, obsolete to much longer than leaves; bracts present or absent; pedicels very short or extended (best seen in fruiting material). Flowers bisexual. Calyx teeth minute or obsolete. Petals white, greenish or yellow, valvate, ovate, spreading. Stylopodium conic to depressed. Fruit globose or ellipsoid, strongly flattened laterally, base cordate, dorsal surface rounded, glabrous (rarely with white hairs); dorsal and lateral ribs usually conspicuous, slender, acute (rarely obsolete); vittae inconspicuous. Seed face plane to concave; endocarp woody. Carpophore usually absent.

<==Hydrocotyle Linnaeus 1753 A61 [incl. H. sect. Euhydrocotyle C06]
    |--H. alata GK00
    |--H. americana Linnaeus 1753 [incl. H. nitens Colenso 1891] A61
    |    |--H. a. var. americana A61
    |    `--H. a. var. heteromeria (Rich.) Kirk 1899 [=H. heteromeria Rich. 1820] A61
    |--H. callicarpa GK00
    |--H. diantha GK00
    |--H. dissecta Hooker 1853 A61
    |--H. elongata Cunn. 1839 [incl. H. concinna Colenso 1885, H. echinella Colenso 1888] A61
    |--H. grammatocarpa LK14
    |--H. hirsuta J87
    |--H. hydrophila Petrie 1897 [=H. tripartita var. hydrophila (Petrie) Cheeseman 1906] WJ82
    |--H. microphylla Cunn. 1839 A61
    |--H. moschata Forster 1786 A61 (see below for synonymy)
    |--H. muscosa Br. ex Rich. 1820 WJ82, A61
    |--H. natans C55
    |--H. novaezelandiae DC. 1830 (see below for synonymy) A61
    |    |--H. n. var. novaezelandiae A61
    |    |--H. n. var. involucrata (Col.) Allan 1961 [=H. involucrata Col. 1887] A61
    |    |--H. n. var. lobulata Kirk 1899 A61
    |    |--H. n. var. montana Kirk 1899 A61
    |    `--H. n. var. robusta (Kirk) Cheesem. 1906 [=H. robusta Kirk 1899] A61
    |--H. pilifera GK00
    |    |--H. p. var. pilifera GK00
    |    `--H. p. var. glabrata GK00
    |--H. pterocarpa Muell. 1855 A61
    |--H. pusilla J87
    |--H. ranunculoides V09
    |--H. rugulosa G04
    |--H. sibthorpioides Lam. 1789 A61
    |--H. sulcata Webb & Johnson 1982 WJ82
    |--H. tripartita Br. ex Rich. 1820 WJ82
    |--H. umbellata H93
    |--H. verticillata [incl. H. verticillata var. triradiata] H93
    `--H. vulgaris K03

Nomen nudum: Hydrocotyle tripartita var. subpilosa Petrie in Allan 1961 WJ82

Hydrocotyle moschata Forster 1786 A61 [incl. H. colorata Colenso 1886 A61, H. compacta C06, H. sibthorpioides var. laciniata Kirk 1899 A61, H. moschata var. parvisolia Carse 1928 A61]

Hydrocotyle novaezelandiae DC. 1830 [incl. H. alsophila Col. 1886, H. amoena Col. 1889, H. dichondraefolia Cunn. 1839, H. intermixta Col. 1885] 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).

[C55] Candolle, A. de. 1855. Géographie Botanique Raisonée: Ou exposition des faits principaux et des lois concernant la distribution géographique des plantes de l’époque actuelle vol. 2. Librairie de Victor Masson: Paris.

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

[G04] Gibson, N. 2004. Flora and vegetation of the Eastern Goldfields Ranges: part 7. Middle and South Ironcap, Digger Rock and Hatter Hill. Journal of the Royal Society of Western Australia 87 (2): 49–62.

[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.

[H93] Hickman, J. C. (ed.) 1993. The Jepson Manual: Higher Plants of California. University of California Press: Berkeley (California).

[J87] Judd, W. S. 1987. Floristic study of Morne La Visite and Pic Macaya National Parks, Haiti. Bulletin of the Florida State Museum—Biological Sciences 32 (1): 1–136.

[K03] Kårehed, J. 2003. The family Pennantiaceae and its relationships to Apiales. Botanical Journal of the Linnean Society 141: 1–24.

[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.

[V09] Verdcourt, B. (ed.) 2009. Additions to the wild fauna and flora of the Royal Botanic Gardens, Kew. XXVI. Miscellaneous records. Kew Bulletin 64 (1): 183–194.

[WJ82] Webb, C. J., & P. N. Johnson. 1982. Hydrocotyle (Umbelliferae) in New Zealand: the 3-foliolate species. New Zealand Journal of Botany 120: 163–168.

Last updated: 31 August 2018.