Dryas drummondii : Yellow Mountain Aven

Scientific Name:

Kingdom: Plantae

Division:

• Tracheophyta (vascular)
• Spermatophyta (seed bearing)
Angiospermae (enclosed seed)

Class: Dicoteldonae (two seed-leaves)

Family: Rosaceae (Rose Family)

Genera: Dryas (Mountain Avens) (Gk. Drus = Oak; referring to the resemblance of the leaves of some species to oak leaves.)

Species: drummondii (Named for Thomas Drummond 1780-1835? a Scottish botanist)

English Name(s):

Yellow Mountain Aven, Yellow Dryas, Drummond Dryas/Mountain Avens

First Nation Names:

Structure:

• Low mat-forming undershrub.
• Branches freely rooting.
• Stems arising from long woody cudex (base).

Leaves:

• Leathery, tardily deciduous (falling) or evergreen.
• Petioled (on a stalk).
• Elliptic to oblong to obovate in shape.
• 9-50mm long by 6-20mm wide.
• Margins coarsely dentate (toothed).
• Dark green and rugose (wrinkly) above, densely tomentose (wooly) below.
• With stipules (appendages) rising from leaf axils, linear-lanceolate in shape, tomentose (wooly).

Reproductive Parts:

• Flowers perfect (bisexual), with regular symmetry, scapose (on leafless stem), and normally solitary.
• Flowers noding when in bloom and never fully opening.
• Hypanthuim (recepticle) saucer shaped.
• Sepals and petals 8-10.
• Stamens (male parts) and pistils (female parts) numerous.
• Petals yellow.

Seed:

• Style persisting and becoming much-elongated and plumose (feathery), and erect in fruit.
• Fruit is an achene (nutlet).

Not to Be Confused With:

• The other Dryas (Mountain Avens). Dryas integrifolia (Entire-leaved Mountain Aven) can be distinguished by its smooth not toothed leaf margins and white petals. Dryas octopetala (Eight-petalled Mountain Aven) can be distinguished by its white petals and narrower leaves.

Physiology:

• Dryas (Mountain Avens) are superbly adapted to the rigours of the exposed areas where they grow. The tough roots are deeply anchored and their nodules contain nitrogen fixing bacteria.
• The leaves with their waxy coating and wooly undersides are designed to conserve moisture and in summer and shed ice in winter.
• The feathery styles permit wide dispersal of seeds.
• The parabolic shape of the flowers which face the sun, focuses the suns energy on the pistil (female parts) heating it up by up to 3.6 C. The warmer temperatures attract pollenating insects whose body temperatures when basking in the flowers may exceed the ambient air temperature by 5-15 C.

Life Cycle:

• Perennial

Seasonal Cycle:

• Leaves tardily deciduous (falling).
• Some leaves are evergreen and will survive the winter.
• Gone to seed by mid-July.

Animal Uses:

Habitat:

• Are a pioneering species in areas recently exposed by receding glaciers.
• Liking calcareous sites.
• Gravelly floodplains, scree slopes, and disturbed roadside gravels.

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