Scientific: Melaleuca citrina (Synonyms: Callistemon citrinus, Callistemon lanceolatus)
A scientific name quagmire: Lyn Craven of the Australian National Herbarium (Novon 16 468-475; December 2006 “New Combinations in Melaleuca for Australian Species of Callistemon (Myrtaceae)”) argued based on genomic research that the differences between the two genera, Callistemon and Melaleuca, are insufficient to warrant them being retained separately and that they should be combined, thus Melaleuca is the preferred genus based on earlier precedence.
Common: lemon bottlebrush
Family: Myrtaceae
Origin: Coastal New South Wales, Victoria and southern Queensland of Australia, usually in bottomland swampy sites.
Pronounciation: Mel-a-LOU-ka ci-TRI-na
Hardiness zones:
Sunset 12-24, cold damage in zone 8-9
USDA 9 (zone 8 with protection)-11
Landscape Use: Floral accent, background, screen, large informal hedge, small street tree, Mediterranean landscape design motifs.
Form & Character: Upright and rounded, stiff and brittle, semi-tropical, oasis.
Growth Habit: Evergreen, woody, perennial broadleaf shrub, upright, 8- to 15-feet tall, moderate growth rate ranging from a large shrub to small multiple-trunked tree. With patience, persistence and effort, lemon bottlebrush can be trained as a standard (single trunk small tree).
Foliage/Texture: Young leaves are reddish and pubescent, mature leaves are dull green, thick and brittle, lanceolate to 4-inches long, nearly sessile, aromatic (lemon fragrance); medium coarse texture.
Flowers & Fruits: Red bottle brush flowers (stamens tower above with protruding bright yellow or red filaments with sometimes yellow anthers) followed by persistent small round nut-like fruit.
Seasonal Color: Yellow or red flowers (red selections seen in America, yellow in Australia) in Spring (some off-season blooms in fall).
Temperature: Winter cold tolerant to 20oF. Suffers significantly during summer if daily temperature exceeds 110oF for extended periods.
Light: Full sun
Soil: Well-drained soil are needed. Highly prone to leaf yellowing (micronutrient deficiency-induced chlorosis) in Phoenix due to alkaline soils, especially if soils are consistently moist (overwatered).
Watering: Infrequent deep irrigations especially during summer.
Pruning: Train lemon bottlebrush rigorously when young to attain upright form if desired. Remove crossing branches, elsewise prune to raise canopy base. Easily manipulated, but has brittle wood.
Propagation: Seed difficult, cutting easy.
Disease and Pests: None that are significant.
Additional comments: Lemon bottlebrush shrubs (citrina means lemons scented) strongly attracts bees when in flower. This species has been responsible for many of the bottlebrush cultivars that are seen in southwestern landscapes (primarily California) today, sometimes as hybrids with other Melaleuca (formerly Callistemon) species. Most of these cultivars have arisen as chance seedlings rather than by deliberate hybridization.
Some of the better known locally-marketed cultivars of lemon bottlebrush include:
The final verdict: In my opinion though, leaf chlorosis (yellowing) caused by moderate to high soil alkalinity and salinity makes this plant mostly useless in Phoenix.
