Branched phacelia (Phacelia ramosissima) COSEWIC assessment and status report: chapter 6

Biology

General

There has been little research on Phacelia ramosissima. The species is a perennial that is well adapted to growing in areas with little precipitation during the growing season. It is said to be a heliotrope because of its manner of turning its flowers to face the sun throughout the day.

Reproduction

The age profile of mature Phacelia ramosissima plants is not known. Bees are known to be major pollinators in California and are probably important in the southern Okanagan (Edgehill Mountain, 2003). Individuals of this species in British Columbia occur in close enough proximity for effective pollen transfer. The plants produce large amounts of seeds, which are found to have good viability and high germination rates in California gardens. Seed viability, dormancy, germination and seedling ecology remain unknown for southern Okanagan habitat.

Survival

Until Phacelia ramosissima populations are monitored, survival factors will remain unknown.

Physiology

Although habitats of this species receive low amounts of precipitation during the growing season, below-ground moisture, which is recharged each winter, is apparently sufficient for vegetative growth and flower and seed production before senescence occurs during mid-summer. Many, but not all, populations occur below limestone rock outcrops.

Movements/dispersal

Short-range dispersal is likely by small mammals or birds and in some cases downslope movement of seeds. Long-range dispersal mechanisms remain unknown.

Nutrition and interspecific interaction

Unknown.

Behaviour/adaptability

Phacelia ramosissima is highly specialized with respect to its habitat in Canada. It occurs only on a narrow (about 1 to 2 m wide) band of talus and rock debris below rock outcrops.

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