Family: Fabaceae
Cassia roxburghii, commonly known as Red Cassia or Red Shower Tree, is a small to medium-sized flowering tree native to the hot, dry regions of southern India and Sri Lanka. It belongs to the legume family (Fabaceae) and is valued for its attractive, salmon-pink to red flowers, which are delicately veined and appear in showy clusters. The tree grows up to 10–15 meters tall, with cylindrical, indehiscent seed pods that can reach 20–30 cm in length. Primarily grown as an ornamental in tropical and subtropical gardens, it is appreciated for its floral display and ability to fix nitrogen in the soil, though it remains uncommon in cultivation outside its native range.
Despite its ornamental appeal, Red Cassia does not appear to pose significant invasive risks in regions like Hawaiʻi. Assessments show no evidence of the species becoming naturalized, weedy, or invasive anywhere in the world. It lacks aggressive reproductive traits—seeds are not adapted for wind, water, or animal dispersal, and the tree does not form dense thickets. While it can produce a persistent seed bank and is intentionally planted, its overall ecological impact is considered low, with no documented negative impacts on agriculture, forestry, or natural ecosystems. As always, proper site selection and monitoring are recommended when planting non-native species.
High Risk Traits:
- Climatic Suitability: Highly suited to tropical or subtropical climates (score 2), native to hot, dry areas.
- Nitrogen Fixing: As a Fabaceae, it fixes nitrogen, which can enrich soil and potentially facilitate invasion.
- Intentional Dispersal: Propagated and planted intentionally as an ornamental species.
- Seed Viability: Produces viable seeds that can be propagated via scarification/soaking.
- Seed Bank Formation: Evidence of a persistent seed bank (>1 year), typical of hard-seeded legumes.
Low Risk Traits:
- Low Invasiveness: No evidence of naturalization, weediness, or invasiveness globally.
- Limited Dispersal: No adaptations for wind, water, bird, or external animal dispersal; large pods and seeds unlikely to be accidentally spread.
- Not a Shade Tolerant: Prefers full sun; not shade tolerant.
- No Vegetative Reproduction: No evidence of reproduction by vegetative fragmentation.
- Low Seed Production: Unlikely to produce >1000 seeds/m² given large pod and seed size.
- Palatable to Wildlife: Consumed by elephants in native range; not toxic to animals.
- Non-allelopathic, Non-parasitic, No spines/thorns, No fire risk: Lacks harmful physical or ecological traits.
