Kellogg’s rush (Juncus kelloggii) COSEWIC assessment and status report: chapter 6

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Biology

General

Juncus kelloggii is an annual species that requires sites that are moist to wet in the winter and spring and dry during the summer. In other parts of the range, this species occurs on sandy to clayey soils. The wet period is necessary for germination and growth, possibly as annual flooding followed by desiccation reduces competition by other plants. Other annual Juncus species do not handle competition well and are therefore usually found growing on bare ground (Ertter 1986).

Reproduction

This annual species is generally self-pollinating (Swab, 1993). In the Juncus triformis complex (J. kelloggii is part of the “kelloggii group” within this complex), higher altitude species were found by Ertter (1986) to require cold treatment for germination. Germination began as early as two days after cold treatment and continued up to two weeks afterward. Ertter (1986) stated that since only a certain percentage of the seeds germinated, there may be seeds in the soil that potentially could germinate at a later time. Each J. kelloggii capsule contains approximately 50 seeds (Ertter 1986). No seed germination experiments were conducted for this report.

Survival

During germination experiments conducted by Ertter (1986) on the Juncus triformis complex, not all seeds germinated in the same year. Therefore, seeds may only germinate in favourable years. The annual life cycle, diminutive size and reduction of flowers in Juncus kelloggii are all factors that could contribute to its survivability in a drought environment (Ertter 1986).

Physiology

The flowers require long daylength to trigger flower production and open in the morning. Seedlings of the J.triformis complex develop leaves and culms after a lag period from the production of cotyledons. The latter could have been due to the artificial growing conditions (Ertter 1986).

Movements/dispersal

Dispersal may be by birds transporting the seeds in their feet and feathers after walking through the muddy habitat (Ertter 1986).

Nutrition and interspecific interactions

Some members of the J. triformis complex require acidic soils such as found in vernal pools. The “kelloggii” group, however, prefers sandy or silty soils (Ertter 1986).

Behaviour/adaptability

Juncus kelloggii may survive unfavourable seasons as drought tolerant seeds (Ertter 1986). It is dependent on an annual cycle that can survive in a habitat that fills in with water, then dries out in the summer. This potentially decreases competition from other species (Ertter 1986).