Blackboard Tree vs

Alstonia scholaris compared with Cocconeis disculus

Key Differences

• Blackboard Tree is Least Concern while is Not Evaluated.

Taxonomic Classification

Rank	Blackboard Tree
Kingdom	Plantae (Plants)	Chromista (Chromista)
Phylum	Magnoliophyta (Flowering Plants)	Ochrophyta (Ochrophyta)
Class	Magnoliopsida (Dicots)	Bacillariophyceae (Bacillariophyceae)
Order	Gentianales (Gentianales)	Achnanthales (Achnanthales)
Family	Apocynaceae	Cocconeidaceae
Genus	Alstonia	Cocconeis
Species	Alstonia scholaris	Cocconeis disculus

Conservation Status

Blackboard Tree

LC — Least Concern

NE — Not Evaluated

Physical Characteristics

Attribute	Blackboard Tree
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Blackboard Tree

Habitat

Inhabits tropical and subtropical moist broadleaf forests and tropical and subtropical dry broadleaf forests within the Oceanian biogeographic realm.

Range

Distributed across Micronesia, Taiwan, and United States.

Habitat

Native to Europe and South America, inhabiting ecosystems characteristic of the region.

Range

Distributed across Brazil, Norway, and Sweden.

Blackboard Tree

The Blackboard Tree (Alstonia scholaris) is a species in the genus Alstonia. It is currently classified as Least Concern on the IUCN Red List. Inhabits tropical and subtropical moist broadleaf forests and tropical and subtropical dry broadleaf forests within the Oceanian biogeographic realm.

Cocconeis disculus is a freshwater and brackish-water diatom in the family Cocconeidaceae, belonging to the class Bacillariophyceae—the diatoms, a group of unicellular photosynthetic algae encased in ornate silica cell walls called frustules. Like all members of the genus Cocconeis, C. disculus is an adnate, epiphytic species, meaning it lives attached to substrates—typically the surfaces of aquatic macrophytes, filamentous algae, and sediment particles—rather than living freely in the water column. The frustule of Cocconeis species is distinctive in its bilateral symmetry and the characteristic difference between its two valves: the rapheless valve (RV) lacks the raphe slit present on the raphe valve (RV), a feature used in species identification. Cocconeis disculus has been documented from freshwater bodies across South America and various parts of the Northern Hemisphere, with distribution reflecting its tolerance of a range of water temperatures and nutrient conditions. Diatoms like C. disculus are foundational components of aquatic food webs, fixing carbon through photosynthesis and providing a nutritious food source for grazing invertebrates, protists, and larval fish. The species also contributes to the biosilica cycle through the production and dissolution of its silica frustule. As a benthic, substrate-attached organism, Cocconeis disculus serves as a sensitive bioindicator of water quality conditions in freshwater monitoring programs. Its conservation status is not formally evaluated.