Lunularia cruciata (L.) Dumort. ex Lindb.

Thallus and Gemma Cup Morphology

Lunularia cruciata produces large, dichotomously branched green thalli with crescent-shaped gemma cups that hold disc-like gemmae. This crescent cup feature is a unique morphological trait that no other thalloid liverworts have.

Thallus Surface Characteristics

The surface of its thallus is shiny, faintly lined, and dotted with tiny air pores. When dried, the thallus becomes yellowish and its margin rolls inward.

Ploidy of Main Plant Body

Like other liverworts, the main plant body (the thallus) is a haploid gametophyte.

Sexual Reproduction Phenology

For L. cruciata, antheridia develop in early spring, archegonia develop in spring, and sporophytes develop in late summer. However, recorded instances of sporophyte development and sexual reproduction are rare and scattered.

Cause of Rare Sexual Reproduction

This pattern is suspected to be caused by anthropogenic spreading of the species, which leads to a disjunctive distribution of antheridia and archegonia.

Sexual Reproduction Structure

When reproducing sexually, four archegonia are arranged in a cross-shaped head (this arrangement is the origin of the specific epithet cruciata), and this head bears diploid sporophyte plantlets.

Asexual Reproduction Mechanism

When reproducing asexually, disc-shaped gemmae are easily dislodged from the gemma cups by splashes of rainwater. The dislodged gemmae can quickly take root and grow in suitably damp locations, which explains why the species is so successful in greenhouses.

Global Distribution Range

Lunularia cruciata has a worldwide distribution, occurring across the continents of Europe, Australasia, Asia, the Americas, and Africa.

Regional Distribution Details

It is common in western Europe, and native to the Mediterranean region, where morphological forms resulting from sexual reproduction are found more frequently. It is also common in California, where it now grows wild, and is known as an introduced weed in gardens and greenhouses in Australia.

New Zealand Introduction History

Ella Orr Campbell believed L. cruciata was introduced to New Zealand sometime after 1867.

Sporophyte Recorded Locations

While sporophytes of L. cruciata are rare overall, they have been recorded in European regions, as well as in South Africa, Argentina, California, India, Japan, and New Zealand.

Typical Habitat Types

Lunularia cruciata grows in damp, shaded, disturbed habitats such as path edges and wall edges. It can act as a nutrient indicator, because it often grows in alkaline and eutrophic to highly eutrophic soil.

Additional Habitat Substrates

Other common habitats include loam, boulders, concrete, exposed tree roots, soil-covered logs, and gaps between sidewalk stones. L. cruciata also grows as a horticultural weed in gardens, greenhouses, and parks.

Environmental Tolerance and Growth Preferences

It is sensitive to frost, and is often found near water, where its gemmae are washed ashore.