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  4. Hypericum perforatum

Hypericum perforatum

Lower Hutt.<br>Photographer: Jeremy R. Rolfe, Date taken: 24/02/2013, Licence: <a target='_blank' href='https://creativecommons.org/licenses/by/4.0'>CC BY</a>. <a class='member-message' href='/nzpcn/why-join-nzpcn/' target='_blank'>Members can view a larger version of this image.</a>
St John’s wort.<br>Photographer: John Barkla, Licence: <a target='_blank' href='https://creativecommons.org/licenses/by/4.0'>CC BY</a>.
Pellucid and black glands on leaves and stem viewed from below. Hutt Valley.<br>Photographer: Jeremy R. Rolfe, Date taken: 27/12/2006, Licence: <a target='_blank' href='https://creativecommons.org/licenses/by/4.0'>CC BY</a>. <a class='member-message' href='/nzpcn/why-join-nzpcn/' target='_blank'>Members can view a larger version of this image.</a>
Hypericum perforatum.<br>Photographer: John Smith-Dodsworth, Licence: <a target='_blank' href='https://creativecommons.org/licenses/by-nc/4.0'>CC BY-NC</a>. <a class='member-message' href='/nzpcn/why-join-nzpcn/' target='_blank'>Members can view a larger version of this image.</a>
Hutt Valley.<br>Photographer: Jeremy R. Rolfe, Date taken: 03/11/2006, Licence: <a target='_blank' href='https://creativecommons.org/licenses/by/4.0'>CC BY</a>. <a class='member-message' href='/nzpcn/why-join-nzpcn/' target='_blank'>Members can view a larger version of this image.</a>
Hutt Valley.<br>Photographer: Jeremy R. Rolfe, Date taken: 03/11/2006, Licence: <a target='_blank' href='https://creativecommons.org/licenses/by/4.0'>CC BY</a>. <a class='member-message' href='/nzpcn/why-join-nzpcn/' target='_blank'>Members can view a larger version of this image.</a>
Black glands on petal margin. Hutt Valley.<br>Photographer: Jeremy R. Rolfe, Date taken: 03/11/2006, Licence: <a target='_blank' href='https://creativecommons.org/licenses/by/4.0'>CC BY</a>. <a class='member-message' href='/nzpcn/why-join-nzpcn/' target='_blank'>Members can view a larger version of this image.</a>
Spring growth. Whanganui. Oct 2012.<br>Photographer: Colin C. Ogle, Licence: <a target='_blank' href='https://creativecommons.org/licenses/by-nc/4.0'>CC BY-NC</a>. <a class='member-message' href='/nzpcn/why-join-nzpcn/' target='_blank'>Members can view a larger version of this image.</a>
Spring growth. Whanganui. Oct 2012.<br>Photographer: Colin C. Ogle, Licence: <a target='_blank' href='https://creativecommons.org/licenses/by-nc/4.0'>CC BY-NC</a>. <a class='member-message' href='/nzpcn/why-join-nzpcn/' target='_blank'>Members can view a larger version of this image.</a>
Stem and leaf node. Lower Hutt.<br>Photographer: Jeremy R. Rolfe, Date taken: 24/02/2013, Licence: <a target='_blank' href='https://creativecommons.org/licenses/by/4.0'>CC BY</a>. <a class='member-message' href='/nzpcn/why-join-nzpcn/' target='_blank'>Members can view a larger version of this image.</a>
Skull and crossbones

Poisonous plant

Environmental Weed

Environmental Weed (2024)

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Common names

St John’s wort

Biostatus

Exotic

Category

Vascular

Structural class

Herbs - Dicotyledons other than Composites

Flower colours

Black, Yellow

Detailed description

Hairless perennial herb to 1 m tall. Roots with slender, creeping rhizomes. Stems singly or severally from base, erect, round with 2 ridges, woody at base, upper branches in opposite pairs at 45 degrees. Leaves in opposite pairs, stalkless, narrow to oval, 10-27 x 1-8 mm, with many translucent glandular dots. Flowerhead a terminal, flat-topped panicle, dense, many-flowered. Flowers star-like, 8-20 mm diam, golden yellow, with 5 black-dotted petals, Dec-May. Stems usually die in autumn, leaving prostrate, barren, leafy shoots, often forming dense mats.

Similar taxa

may be confused with many other closely related Hypericum spp, 5 adventive and 2 native. The native species lack black glandular dots, and are low to mat forming.

Habitat

Terrestrial. Disturbed short tussockland, herbfield, bare land.

Conservation status

Not applicable

Detailed taxonomy

Family

Hypericaceae

Authority

Hypericum perforatum L.

Ecology

Flowering

December, January, February, March, April, May

Year naturalised

1869

Origin

Eur, W Asia, N Afr

Reason for introduction

Accidental

Tolerances

Tolerates hot to cold temperatures, damp and drought, wind damage and is not grazed (poisonous).

Life cycle and dispersal

Perennial. Relatively long-lived. Reproduces from seed and rhizomes; numerous seeds are contained in capsules. Seeds via wind (minor), possibly livestock. Rhizomes via soil and water movement.

Wetland plant indicator status rating

Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]

UPL: Obligate Upland

Rarely is a hydrophyte, almost always in uplands (non-wetlands).

Other information

Etymology

hypericum: From the Greek hyper (above) and eikon (picture), the plant was hung above pictures to ward off evil spirits

perforatum: From the Latin perforatus ‘pierced with holes’, depending on the species this may refer to the foliage covered in punctate oil glands

Environmental Weed (2024)

This plant is named in a list of 386 environmental weeds in New Zealand 2024 prepared by DOC. 759 candidate species were considered for inclusion on this new comprehensive list of environmental weeds in New Zealand. The species considered were drawn from published lists of weed species, lists of plants that must be reported or managed by law if observed, existing national and regional programmes and agreements for pest management, and species already managed by the Department of Conservation (DOC). Candidate species were then assessed to see if they were fully naturalised and whether they have more than minor impacts in natural ecosystems. Read the full report here.

NVS code

The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.

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