Common Quillwort vs Lǎohǔ

Isoetes lacustris compared with Panthera tigris

Key Differences

Common Quillwort is Least Concern while Lǎohǔ is Endangered.

Taxonomic Classification

Rank	Common Quillwort	Lǎohǔ
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	Felidae (Cats)
Genus	Isoetes	Panthera (Big Cats)
Species	Isoetes lacustris	Panthera tigris

Conservation Status

Common Quillwort

LC — Least Concern

Lǎohǔ

EN — Endangered

Population: ~4.5K

Trend: Increasing ↑

Physical Characteristics

Attribute	Common Quillwort	Lǎohǔ
Diet	—	Carnivore
Average Lifespan	—	20 years
Average Length	—	3.0 m
Average Weight	—	220.0 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).

Lǎohǔ

Habitat

Found across multiple habitat types including tropical and subtropical moist broadleaf forests, tropical and subtropical dry broadleaf forests, and tropical and subtropical grasslands and savannas, among 6 distinct biome types spanning the Neotropic and Oceanian realms. Populations are also found in montane and highland environments at higher elevations.

Range

Distributed across Colombia and Ecuador. Currently classified as Endangered 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.