Clusterspike False Indigo vs Coastal Silver-stiletto

Amorpha crenulata compared with Acrosathe annulata

Key Differences

• Clusterspike False Indigo is Critically Endangered while Coastal Silver-stiletto is Least Concern.

Taxonomic Classification

Rank	Clusterspike False Indigo	Coastal Silver-stiletto
Kingdom	Plantae (plante)	Animalia (animal)
Phylum	Magnoliophyta (Flowering Plants)	Arthropoda (arthropodes)
Class	Magnoliopsida (Dicots)	Insecta (insecte)
Order	Fabales (Legumes & Allies)	Diptera (Diptera)
Family	Fabaceae	Therevidae
Genus	Amorpha	Acrosathe
Species	Amorpha crenulata	Acrosathe annulata

Conservation Status

Clusterspike False Indigo

CR — Critically Endangered

Coastal Silver-stiletto

LC — Least Concern

Physical Characteristics

Attribute	Clusterspike False Indigo	Coastal Silver-stiletto
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Clusterspike False Indigo

Habitat

Typically found in diverse terrestrial habitats from tropical forests to temperate regions.

Coastal Silver-stiletto

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

Clusterspike False Indigo

Amorpha crenulata, known as clusterspike false indigo or crenulate lead plant, is a critically endangered flowering shrub in the family Fabaceae with a highly restricted distribution confined to Miami-Dade County in southern Florida, USA. This species represents one of North America's rarest plants, with remaining populations numbering in the hundreds of individuals occurring in pine rockland habitat, an ecosystem itself ranked among the most imperiled in the United States. Pine rocklands are fire-dependent communities on exposed oolitic limestone, characterized by an open canopy of slash pine over diverse understory, and have been reduced to less than two percent of their historical extent by urban development in the Miami metropolitan area. Amorpha crenulata produces elongated spikes of small purple flowers typical of the genus and was historically more widespread across the Miami Rock Ridge before land development eliminated most habitat. Current populations exist primarily within Everglades National Park and a few private preserves. Its Critically Endangered status reflects the tiny remaining population, extreme habitat restriction, ongoing threats from urbanization, altered fire regimes, and sea-level rise that threatens low-elevation limestone habitats. Conservation efforts focus on habitat protection, controlled burning to maintain pine rockland structure, and ex situ seed banking.

Coastal Silver-stiletto

Coastal silver stiletto (Acrosathe annulata) is a slender robber fly in the family Therevidae, native to northwestern Europe, including the United Kingdom, France, the Netherlands, Belgium, and Scandinavia. Adults are found on coastal sand dunes and sandy heathland, where they perch on bare sand to ambush small flying insects. Stiletto flies in the family Therevidae are characterised by a slender body, long pointed abdomen, and predatory habits; adults prey on a variety of small dipterans and other flying insects during warm, sunny periods. Larvae develop in sandy soil, where they are also predatory, feeding on other invertebrate larvae. Acrosathe annulata is a habitat specialist restricted to open, sandy coastal habitats with sparse vegetation—environments that have declined substantially across northwestern Europe due to dune stabilisation, recreational disturbance, and the cessation of traditional dune management. The IUCN lists it as Least Concern, though regional conservation bodies in the United Kingdom have flagged population declines. It is considered an indicator of high-quality coastal sand dune habitats and is monitored through national invertebrate surveys.