Hypericum canariense Biology

Hypericum canariense Biology...

Taxonomy
Native Range
Growth
Reproduction
Toxicity
References

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A 1.5m tall plant on the island of Gran Canaria.

Taxonomy:

Hypericum canariense L. is in the family Hypericaceae (previously Guttiferae), which is also recognized as a subfamily of the Clusiaceae. Common names include Canary Island St. Johnswort (or Canary Island St. John's Wort) and, in Spain, Grenadillo or Hyperico. This is a separate species from the common St. Johns Wort (Hypericum perforatum) used in herbal remedies, and referred to as the range pest 'Klamathweed'. Hypericum perforatum is a smaller, herbaceous plant, and a common weed in both the United States and Australia.

H. canariense (green in foreground) growing on
Tenerife. (Photo by K. Dlugosch - Aug 2002)

Native Range:

H. canariense is native to the western five of the Canary Islands, ~100 km West of Morocco. On these five islands, H. canariense is a common plant in the wetter areas (generally the North side of each island), where it is found in coastal scrub and laurel forests between 150-800m in elevation. These islands are volcanic in origin and are characterized by steep, often unstable slopes.

Previous collections (dots) of H. canariense.

Growth:

H. canariense is a multi-stemmed perennial shrub, and may grow to 3 meters in height. Given favorable conditions, it may grow to over a meter in its first year.

It has waxy, lanceolate leaves with a prominent midvein. The leaves grow in an opposite orientation (two leaves, or occasionally three, emerge from the same node on a stem). The foliage is green throughout the winter (may be reddish when young), turning orange in the summer, and dropping by late summer.

Like other members of this genus, H. canariense can reproduce asexually via underground rhizomes. Flowers and fruits may be produced in the first year of growth.

Reproduction:

From April to June, H. canariense produces showy terminal clusters of orange-yellow flowers. The flowers are approximately 1.5 cm across, with five sepals, five petals, three stigmas (sometimes four), and numerous anthers. The dry, capsule fruits mature and dehisce from July through August, releasing hundreds of tiny seeds (1 mm in length) with no obvious adaptations for dispersal. Plants may take as little as one year to grow from seed to flowering adult.

This species can both self-pollinate and outcross, in addition to spreading via vegetative reproduction. Production of seeds via apomixis (without pollen) does not appear to be possible (see Matzk et al. 2003). Approximately 80% of seeds will germinate given light and continuous moisture, though this variable from site to site and year to year (K. Dlugosch, pers obs).

Flowers from San Mateo Co., California.
(Photo by J. Wade - Summer 2001)

Fruit from San Diego, CA.
(Photo by M. Platter-Rieger - Summer 2002)

Toxicity and Hypericin:

There does not appear to be published information about the toxicity of this species. K. Dlugosch and collaborator S. Crockett (Karl-Franzens University, Austria) are currently investigating its chemical content and defensive properties.

Hypericin has been isolated from H. canariense in its native range (Mederos-Molina 2002), however it appears to occur in low concentrations relative to H. perforatum, or not at all in some of our greenhouse-reared plants (K. Dlugosch, J. Stewart, S. Crockett, unpubl data).

References:

Bramwell, D. and Z. Bramwell (1984). Wildflowers of the Canary Islands. Stanley Thornes Ltd., Cheltenham.

Hickman, J.C. (1996). The Jepson Manual: Higher Plants of California. University of California Press. Berkeley.

Jupp, D., D. Briese, et al. (1997). St. John's Wort: Hypericum perforatum L.: Integrated control andmanagement. Plant Protection Quarterly 12(2): 51-108.

Matzk, F., K. Hammer and I. Schubert. (2003). Coevolution of apomixis and genome size within the genus Hypericum. Sexual Plant Reproduction 16: 52-58.

Mederos-Molina, S. (2003). Micropropagation of Hypericum canariense L. for the production of Hypericin. Biotechnology in Agriculture and Forestry 51: 95-117.

Robson, N. (1968). Guttiferales. 109. Guttiferae (Clustaceae). Flora Europaea. Cambridge University Press, Cambridge.

Schaeffer, H. (1963). Plants of the Canary Islands. Buchhandlung F. Kutscher, Ratzeburg.