rhodo – rose

dendron – tree

Native range: Europe, Australia, North America, and Asia

Leaves:

• alternate, often clustered at ends of shoots
• entire margin
• often scales or hairs on lower side of leaf

Flowers:

• umbel-like inflorescences (trusses) clustered at ends of branches
• flowers and bell-shaped (campanulate) or funnel-shaped (infundibulum)
• 5 sepals often fused at base
• 5 petals (sometimes 10) fused at base and tubular
• 10 stamens (rarely up to 27)
• anthers open at pores; pollen is thread-like
• one style, long and curved
• flower bud protected by scales

Fruit:

• dry capsules
• seeds often with wings

Other characteristics:

• shrubs or up to 100ft trees
• evergreen or deciduous
• leaf buds obvious in winter
• flowers bloom on previous year’s growth (so gardeners prune right after flowering)

Relevant info:

• 850 species (not all hardy), thousands of cultivars
• genus includes azaleas
• R. macrophyllum is the state flower of WA

Ecology & Adaptations:

• R. macrophyllum
  • moist woods, sea level to moderate elevations in the mountains
  • west of the Cascades crest in WA, BC, south to CA
• fire resilient – re-sprouts well after fire from stem bases or shallow, tuber-like root crown
• tolerates low-nitrogen soil w/ help of mycorrhizal association
• shallow roots maintain access to O₂ for respiration, even in moist forests
• seed dispersal – winged-seeds aid dispersal by wind