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Native Plant Propagation Guidelines:
forbs

Allium amplectens (slim-leaf onion)

Category: 
forbs
n/a

Perennial herb from an egg-shaped to nearly globe-shaped, scaly bulb, the outer scales brownish to grey, with a wavy, fibrous network, the inner scales red or white; 10-40 cm tall.

2 to 4 basal leaves, withering early, linear, channeled to cylindric, shorter than the flowering stem, very slender, smooth, margins entire; stem leaves lacking.

Inflorescence a compact, often head-like, terminal umbel of several to many, stalked flowers above 2 to 3 membranous, egg-shaped bracts, the stalks  0.5-1.5 cm long; flowers white to pink, saucer shaped, of 6 distinct tepals, the tepals 5-9 mm long, lanceolate with pointed tips, spreading, in fruit becoming papery and folding over the ovaries; stamens 6, nearly as long as the tepals; pistil 1, 3-chambered.

Seed capsules are more or less egg-shaped, 3-lobed, with 6 low, rounded crests; seeds 6 or fewer, black.

Most Allium amplectens on Vancouver Island are triploids, which produce seeds by apomixes, but near the coast, a tetraploid variety occurs infrequently, with a darker pink colouration (Wheeler).

Scientific Name: 

Allium amplectens Torr.

Family: 
Liliaceae
English Name: 
slim-leaf onion
Other Names: 
narrowleaf onion or clasping onion

Geographical Range and Habitat Requirements

Ecological Setting: 

Vernally moist rocky bluffs and meadows in the lowland zone (Douglas et al, 2001). Also found on coastal bluffs, rock faces and sandy spits.

Soil Texture: 

Vernally moist rocky bluffs and meadows in the lowland zone (Douglas et al, 2001). Also found on coastal bluffs, rock faces and sandy spits.

Soil Reaction and Salinity: 

Tolerates salt water influence on coastal bluffs, rock faces and sandy spits.

Moisture Regime: 

Very xeric.

Shade Tolerance: 

Prefers full sun.

BEC Zone and GOE Community Status: 

Prefers full sun.

Uses

Landscaping: 

Showy blooms, especially the tetraploid variety, suitable for container planting, probably for the rock garden .

First Nations: 

Allium spp bulbs were eaten by several indigenous groups. They were eaten both raw and steamed in pits lined with pine boughs, covered with lichens and alder boughs (Turner, 1995).

Seed Propagation

Flowering Time: 

Mid-June

Fruit Ripening Time: 

Allium spp bulbs were eaten by several indigenous groups. They were eaten both raw and steamed in pits lined with pine boughs, covered with lichens and alder boughs (Turner, 1995).

Seed Collection Time: 

Late June-July.

Number of Seeds per Kilogram: 

450-650/gram

Fruit and Seed Collection and Extraction: 

Late June-July.

Seed Storage: 

Clean seed is stored in controlled conditions at 40 degrees Fahrenheit and 40% relative humidity (Hunt et al.)

Fruit/Seed Dormancy and Treatment: 

Cold, moist stratified in vermiculite at approximately 44F (Hunt et al.).

Vegetative Propagation

Method Success Rate Time of Collection
Softwood cuttings n/a n/a
Semi-hardwood cuttings n/a n/a
Hardwood cuttings n/a n/a
Root cuttings n/a n/a
Suckers n/a n/a
Plant division n/a n/a

 

 

Outplanting Characteristics and Requirements

Alliums spp generally prefer a sunny position in a light well-drained soil. The bulbs tend to rot when grown in cool wet climates, even if they are given sharp drainage. This species is best in a cold frame and given a dry summer rest. The bulbs should be planted fairly deeply. Most members of this genus are intolerant of competition from other growing plants (PFAF).

Seed and Cutting Propagation Techniques

Seed was directly sown into 1.5" deep flats containing a potting mixture of approximately 1:1:1:2 sand:pumice:peat moss:fir bark mixture. Flats were placed in an outdoor cold frame from late-fall though spring. Most seedlings were transplanted into various sized pots ranging form D-pots to 3x4" plastic containers (some seedlings were not transplanted) using the same potting mixture. The active growth phase can be somewhat extended by misting plants after the last spring rains, but care must be taken not to encourage rot. Dormancy can be induced by letting pots dry-down and then placing in dry storage until the following fall rains. Plants should be allowed to go dormant by early summer. Better growth may be obtained during the first year by avoiding transplanting (seed directly into larger containers rather than flats). Based on results of direct seeding in the field, better above and below ground growth may be obtained by planting in native soil (e.g. loam) rather than potting soil. Loam appears to have lower fluctuations in moisture and temperature that stress seedlings and reduce growth during the first year. Growth from seed to dormant seedling follows the first fall rains through the spring-summer dry-down.

  • Establishment Phase: Initial germination was observed within 2 weeks; Germination rates were relatively low: for seed cold, moist stratified in vermiculite at approximately 44F. Small bulbs (2-6mm in diameter) will be produced within 6-8 months.
  • Length of Establishment Phase: Transplantable sprouts were established within approximately 3-4 weeks.
  • Active Growth Phase: Active growth was observed following the onset of autumn rains (seed swelling) until drying down (die-back and dormancy) occurred in late spring/early summer. The length of the active growth phase can be somewhat controlled with irrigation, but this species requires summer dormancy.
  • Length of Active Growth Phase: 6-8 months (late fall - early summer)
  • Hardening Phase: Hardening is not necessary as the active growth phase starts with the onset of fall rains and plants senesce around the end of spring or beginning of summer.
  • Harvesting, Storage and Shipping: Individuals go dormant following spring-summer dry down and die back. Dormant individuals were placed in dry storage at 60-70ºF
  • Length of Storage: 3-5 months
  • Other Comments: Transplanted seedlings showed some sign of stress and seedlings transplanted earlier showed more vigorous growth subsequent to transplanting. Seed sown directly in the field showed above and below ground growth rates comparable too, or better than seed grown under controlled conditions in well-drained potting soils. Heavier native soils may provide better growing conditions when kept moist compared to well-drained potting soils whose moisture and temperature may fluctuate more readily (Hunt et al, 2006).

 

Additional Information and Photos

For more information and pictures, visit the E-Flora BC website at www.eflora.bc.ca.

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