Classification
 Subordinate Taxa
 Nomenclature
Scientific Name:
Hypericum mutilum L., Sp. Pl. 787 (1753)
Vernacular Name(s):
small-flowered hypericum
 Description

Herbaceous annual or perennial, not rhizomatous, up to 0.55 m high. Stems erect, usually solitary, decumbent at base, up to 2.2 mm diam., quadrangular, 4-lined, black glands absent. Leaves 7.0-33.0 mm long, 3.0-13.0 mm wide, ovate, oblong, elliptic, ovate-oblong or ovate-elliptic, glabrous, reticulate tertiary veins absent; pellucid glands conspicuous; black glands absent; apex acute, subacute or obtuse; margin entire; base subcordate, truncate or obtuse; sessile. Inflorescence terminal, dichasial cymes, flowers few to many (greater than 50), corolla 3.0-4.0 mm diam. Pedicels 0.2-2.0 mm long. Bracteoles 1.0-2.0 mm long, 0.3-0.4 mm wide, subulate, apex acute. Sepals 5, 1.2-3.5 mm long, 0.3-1.0 mm wide, unequal, accrescent, lanceolate, oblong, elliptic-oblong, linear-lanceolate or linear-elliptic; pellucid glands present; black glands absent; apex acute or subacute; margin entire. Petals 1.8-2.5 mm long, 0.5-1.2 mm wide, longer than sepals, elliptic or elliptic-oblong, pale yellow, black glands absent, persistent after anthesis. Stamens not in bundles 6-16, 1.6-3.0 mm long, shorter than petals; anthers c. 0.2 mm long, anther gland absent. Ovary 1.5-1.8 mm long, 0.5-1.0 mm wide, oblong-ellipsoid. Styles 3, 0.3-0.5 mm long, longer than ovary. Fruit capsule, 3.5-4.7 mm long, 1.6-2.5 mm wide, oblong-ellipsoid, yellow-brown, seed outline protruding through wall. Seeds 0.4-0.6 mm long, c. 0.2 mm wide, oblong, terete, light yellow-brown, ribs absent, apices obtuse or rounded.

 Recognition

Distinguished by its usually solitary, 4-angled stems, the stem base being decumbent and rooting, absence of black glands, the petals being shorter than the sepals, 3 styles, and the mature capsules being thin-walled, oblong-ellipsoid and having the seed outline visible.

 Habitat

Mainly occurs in wet habitats such as roadside ditches, swamps, marshes, and wetlands, where it is often interspersed amongst other vegetation.

 Biostatus
Exotic
Number of subspecific taxa in New Zealand within Hypericum mutilum L.
CategoryNumber
Exotic: Fully Naturalised1
Total1
 First Record

Healy (1972, p. 189). Voucher: CHR 17443, 1967.

 Phenology

Flowering: Dec.–Feb.

 Bibliography
Healy, A.J. 1972: Weedy St John's Worts (Hypericum spp.) in New Zealand. N.Z.Weed and Pest Control Conf.Proc. 25: 180–190.
Heenan, P.B. 2014: Hypericaceae. In: Breitwieser, I.; Brownsey, P.J.; Heenan, P.B.; Wilton, A.D. (ed.) Flora of New Zealand — Seed Plants. Fascicle 1. Manaaki Whenua Press, Lincoln.
Linnaeus, C. 1753: Species Plantarum. Impensis Laurentii Salvii, Stockholm.
Robson, N.K.B. 1990: Studies in the genus Hypericum L. (Guttiferae) 8. Sections 29. Brathys (part 2) and 30. Trigynobrathys. Bulletin of the British Museum (Natural History). Botany 20: 1–151.