Scientific Name: Stachytarpheta spp.
Common Names: Porterweed, Snakeweed, Velvetberry, Rat's Tail
Duration: Annual, Perennial
Growth Habit: Subshrub, Herb/Forb
Hawaii Native Status: Introduced. These naturalized wildflowers are native to the tropical Americas.
Flower Color: Light to dark blue, White
Height: 3 to 6 feet (0.9 to 1.8 m) tall
Description: The flowers open only a few at a time on up to 20 inch (50 cm) long, slender, curved flower spikes. The individual flowers are tubular and have 5 lobes and a paler center. The leaves are simple, green, opposite, petiolate, and toothed. The stems are weakly erect and often woody near the base.
Four very similar Stachytarpheta species are found here in Hawaii, and they can be difficult to identify, especially since they hybridize with each other. Branched Porterweed (Stachytarpheta australis) has pale blue or white flowers and hairy flower stalks and lower leaf surfaces. Cayenne Porterweed (Stachytarpheta cayennensis) has blue or white flowers and hairless flower stalks and lower leaf surfaces. Light-blue Snakeweed (Stachytarpheta jamaicensis) has has blue or purple flowers and thicker, hairless flower stalks and fleshy leaves with hairless lower leaf surfaces. Nettleleaf Velvetberry (Stachytarpheta urticifolia) has dark blue or purple flowers and hairless flower stalks.
Here in Hawaii, Porterweed grows along roadsides and in disturbed areas at lower elevations.
Butterfly Plant – The flowers attract butterflies.
Kingdom: Plantae – Plants
Subkingdom: Tracheobionta – Vascular plants
Superdivision: Spermatophyta – Seed plants
Division: Magnoliophyta – Flowering plants
Class: Magnoliopsida – Dicotyledons
Family: Verbenaceae – Verbena family
Genus: Stachytarpheta Vahl – porterweed
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