img

Metrosideros polymorpha

Gaudich. (1830)

This name is accepted

Kingdom: Viridiplantae Phylum: Magnoliophyta Class/Clade: Eudicot-Rosids Order: Myrtales Family: Myrtaceae Genus: Metrosideros

‘ōhi‘a [ohia], ‘ōhi‘a lehua [ohia lehua], lehua

img

Description

Key Characters: Fruit a capsule; flowers in terminal cymes; sepals and petals distinct; staminal filaments distinct; leaves opposite; petioles ± as long as blades or less; expanding vegetative buds rounded at the tip; leaves not rugose, glabrous or lower surface woolly or appressed pubescent.

Growth Form: Small erect to prostrate shrubs to tall trees.

Stems: Bark usually rough and fissured, separating in thick flakes, sometimes smooth and separating in long thin strips, vegetative buds obovoid.

Roots: Adventitious aerial roots often present.

Leaves: Leaves simple. Opposite. Blade shape obovate to orbicular or sometimes elliptic, broadly ovate, or ovate, 1–8 cm long, 1–5.5 cm wide. Apex rounded or sometimes obtuse to acute. Base cuneate to cordate. Upper surfaces glabrous; lower surfaces glabrous or woolly or appressed pubescent. Margins entire and revolute to flat. Several pairs of raised veins radiating from base. Petioles usually short, usually much less than ⅓ as long as blades, 1–16 mm long, 1–3 mm wide. Stipules vestigial or absent.

Flowers: Flowers in inflorescences of 2–5 pairs of cymules, glabrous or appressed or woolly pubescent; peduncles 7–18 mm long, 1–3 mm wide, pedicels 2–8 mm long, 1–2 mm wide, bracts broadly ovate to suborbicular, 5–10 mm long, 3–5 mm wide; hypanthium 3–7 mm high, 3–8 mm wide. Flowers red, pink, orange, bisexual (perfect), actinomorphic. Sepals rounded to triangular, 1.5–4 mm long, 1.5–3 mm wide. Petals obovate to orbicular, 2.5–5 mm long, 2–4.5 mm wide. Stamens 1–3 cm long. Ovary nearly superior; style 1.3–3 cm long.

Fruit: Capsules slightly included to exerted; fruiting hypanthium 3–8 mm long and wide; pubescent or glabrous.

Ploidy: 2n = 22*

Habitat: Inhabiting many ecological situations; early successional stages to a dominant species of shrublands and mesic to wet forest.

Elevation Range: 0–2,200 m.

Historical Distribution

Uses and Culture

USES

PROPAGATION/CULTIVATION

  • The tiny seeds of Metrosideros polymorpha are contained in a cup-like capsule about 1/4 inch in diameter. The capsule turns brown as the seeds mature. Collect the seed capsules when they are mature, but before they split open. Put the them in a paper bag or envelope and keep them dry. When the capsules open, the minute dust-like seeds will fall out.
  • Some researchers have found that light is required for germination of Metrosideros polymorpha seed while others have found that it greatly improves germination. Bright light, however, is not required for germination; Metrosideros polymorpha seeds germinate well at low light levels. In any case, it is best to sow Metrosideros polymorpha seeds on the surface of the medium. Drake found that Metrosideros polymorpha seeds germinate at any constant temperature from 50 to 93 degrees F. However, the fastest germination was at a temperature of 72 degrees and the slowest at 93 degrees. Interestingly, he also found that seeds from plants with fuzzy leaves germinated somewhat faster overall and better at higher temperatures. (Burton 1982; Drake 1993)
  • Use a moist sterile potting medium such as 1 part potting mix to 1 part fine cinders (NTBG 1993). Stratton's survey respondents suggested either the same mix as NTBG or a mix of 3 parts #2 perlite to 1 part Sunshine Mix #4. After sowing the seeds, water the medium as gently as possible; a mist system is ideal. Drake germinated seeds on find basalt sand using 6 seconds of mist every 3 minutes. Keep the medium moist and place the seed containers in a covered, shady location to control soil moisture and reduce damage from rain.
  • Both Drake and Burton found that a less than 20% of the seeds in a Metrosideros polymorpha capsule are viable; most of the seeds do not contain embryos. The viable, embryo-containing seeds are plumper than the others. Burton feels that the low percentage of viable seeds may be a result of partial self-incompatibility since this has been shown in some New Zealand members of this genus. This low seed viability rate results in a low germination rate. The most current NTBG publication (1996) states that the seeds germinate in 7 to 14 days. Drake also found that the majority of viable seeds germinated in 10 days and over 90% germinated within 15 days. Criley gives 10 days as the germination time.
  • Metrosideros polymorpha seeds should be sown while they are fresh since storage greatly reduces seed viability. Seeds stored at room temperature (55-84 degrees F) and ambient humidity (58-98%) for only a few months show significant losses in viability. If it is necessary to store the seeds, Stratton et al suggests removing them from the capsules as outlined above and storing them in a paper bag or envelope. Then place the paper container in an airtight container with desiccant in a cool, dry location. Some seed will germinate even after 3 years of storage in a refrigerator. (Bornhorst 1996; Burton 1982; Criley 1998; Criley 1999; Drake 1993; NTBG 1993; NTBG 1996; Stratton 1998; Yoshinaga 1998)
  • Metrosideros polymorpha can be grown from cuttings. Use tip or stem cuttings that are about 1/4 inch in diameter and 4 to 6 inches long. Criley recommends taking tip cuttings from vigorous, recently matured growth. Reduce water loss by removing portions of the leaves on the upper part of the cutting.
  • Rauch et al tested 4 dilutions of rooting hormone with a 2 to 1 indolebutyric acid (IBA) to naphthaleneacetic acid (NAA) ratio (Dip'n Grow) on 4 inch cuttings of yellow flowered Metrosideros polymorpha. The dilutations ranged from 500 to 5,000 parts per million (ppm) of IBA. Vermiculite was used as the rooting medium and the cuttings were placed under intermittent mist of 6 seconds every 2 minutes. They reported that best results were obtained with 2,000 ppm IBA. One hundred percent of the cuttings in that treatment rooted and they had the longest average root length of all of the treatments. They found that the higher concentration was detrimental to both root length and rooting percentage.
  • Criley reports success with rooting hormones in solution having a 2 to 1 ratio of IBA to NAA. In this work, successful total auxin concentrations ranged from 2,000 parts per million (ppm) to 4,000 ppm, but higher concentrations may be needed for more difficult to root varieties. Bornhorst suggests dipping the cutting in a strong rooting hormone such as 10% Dip-N-Gro for 10 seconds.
  • Put the cuttings in a very well draining medium. Some recommended media are 1 part perlite to 1 part peat moss to 1 part vermiculite or 100% perlite. Criley uses either 1 part coarse perlite to 1 part vermiculite or 100% vermiculite.
  • Bornhorst states that cutting material from some individual plants roots more reliably than material from others. Criley suggests that cultivated forms may root more easily. (Bornhorst 1996; Criley 1998; Criley 1999; Rauch 1997; Stratton 1998)
  • Metrosideros polymorpha can be grown from air layers. Use standard air layering techniques, but use a strong rooting hormone. Bornhorst recommends a 10% solution of Dip-N-Gro.
  • Tanabe and Frazier report that the ring girdle air layer technique was successful on vigorously growing branches of younger plants. In their work, they used 3 to 4 foot long air layers. They tested a range of indolebutyric acid (IBA) concentrations and found that a 3% IBA talc dust (30,000 ppm) improved both rooting percentage and root quality of Metrosideros polymorpha air layers. This level of rooting hormone produced an 80% rooting rate after 15 weeks. They found that higher levels of IBA reduced rooting success.
  • Some individual plants seem to air layer more easily than others. Bornhorst suggests that the presence of aerial roots indicates that the plant may be propagated by air layering relatively easily. (Bornhorst 1996; Tanabe 1985; Stratton 1998) [Data from Herring, E. C., & Criley, R. A. (2003). The Hawaiian Native Plant Propagation Web Site: Developing a Webbased Information Resource. HortTechnology, 13(3), 545-548. https://www.ctahr.hawaii.edu/hawnprop/]

Ethnobotanical Images (4)

img
img
img
img
img
img
img
img
img
img

Natural History

Statewide Status

Endemic

Island Status

Kaua'i Endemic
O'ahu Endemic
Molokai Endemic
Lana'i Endemic
Maui Endemic
Hawai'i Endemic

Dispersal Agents


Pollinators

Notes

  • There are a number of variations on the Hawaiian vernacular names ʻohiʻa and lehua that refer to both Metrosideros macropus and Metrosideros polymorpha. ʻOhiʻa hakea, ʻohiʻa kea, ʻohiʻa lehua puokeo, lehua haʻakea, lehua kea, and lehua pua kea all refer to ʻohiʻa with white flowers; ʻohiʻa ʻulaʻula refers to ʻohiʻa with red flowers; ʻohiʻa ʻapone and lehua ʻapane refer to ʻohiʻa with dark red blossoms; lehua mamo refers to ʻohiʻa with yellow flowers; lehua lau liʻi or ʻohiʻa lau liʻi refers to a form of ʻohiʻa with very small leaves; Iehuakamakua or ʻohiʻa ku ma kua is a form with sessile cordate leaves; lehua hamau (lit., silent lehua) and ʻohiʻa hamau are poetic references to the lehua tree; ʻohiʻa ko refers to an ʻohiʻa log to be made into a canoe; and ʻohiʻa Laka is a legendary tree that bore one red and one white flower.

Bibliography

Name Published In: Voy. Uranie: 482 (1830)

Occurrences (274)

Back to Top