Common Quillwort vs Polar bear

Isoetes lacustris compared with Ursus maritimus

Key Differences

Common Quillwort is Least Concern while Polar bear is Vulnerable.

Taxonomic Classification

Rank	Common Quillwort	Polar bear
Kingdom	Plantae (植物)	Animalia (动物界)
Phylum	Tracheophyta	Chordata (脊索动物门)
Class	Lycopodiopsida (石松纲)	Mammalia (哺乳動物)
Order	Isoetales (水韭目)	Carnivora (食肉目)
Family	Isoetaceae	Ursidae (Bears)
Genus	Isoetes	Ursus (Bears)
Species	Isoetes lacustris	Ursus maritimus

Conservation Status

Common Quillwort

LC — Least Concern

Polar bear

VU — Vulnerable

Population: ~26.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	Common Quillwort	Polar bear
Diet	—	Carnivore
Average Lifespan	—	25 years
Average Length	—	2.4 m
Average Weight	—	450.0 kg

Habitat & Geographic Range

Common Quillwort

Habitat

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

Range

Found across Europe (5 countries) and North America (Canada, United States).

Polar bear

Habitat

Found across multiple habitat types including temperate broadleaf and mixed forests, temperate coniferous forests, and boreal forests and taiga, among 4 distinct biome types within the Palearctic biogeographic realm. Populations are also found in montane and highland environments at higher elevations.

Range

Found in Norway. Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

Common Quillwort

The Common Quillwort, <em>Isoetes lacustris</em>, is an aquatic vascular plant in the family Isoetaceae, a relict lineage representing one of the most ancient groups of vascular plants, related to the giant lycopsid trees of the Carboniferous period. It is native to Europe and North America, where it typically grows submerged in cool, clear, oligotrophic lakes and slow rivers on sandy or gravelly substrates at low to mid elevations. <em>Isoetes lacustris</em> is characterized by its rosette of quill-like, hollow, dark green leaves emerging from a lobed corm-like base, typically reaching 10 to 20 centimeters in length. The sporangia, which produce megaspores and microspores, are embedded at the swollen bases of the leaves. The species reproduces via spores and is entirely submerged, absorbing carbon dioxide and nutrients from the sediment and water column. It is highly sensitive to water quality deterioration, including eutrophication and acidification, and its presence is considered an indicator of pristine lacustrine conditions. The Common Quillwort is assessed as Least Concern on the IUCN Red List. Biological traits such as average lifespan, body size, and specific dietary preferences remain poorly documented for this species.