| Lunularia | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Plantae |
| Division: | Marchantiophyta |
| Class: | Marchantiopsida |
| Order: | Lunulariales H.Klinggr. |
| Family: | Lunulariaceae H.Klinggr. |
| Genus: | Lunularia Adans. |
| Species: | L. cruciata |
| Binomial name | |
| Lunularia cruciata (L.) Dumort. ex Lindb. | |
| Synonyms | |
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Lunularia is agenus ofliverworts whose only species isLunularia cruciata, thecrescent-cup liverwort.[1]Lunularia is either the only genus in theorderLunulariales,[2] or may be placed in the orderMarchantiales.[3][4][5] The name, fromLatinluna, moon, refers to the moon-shapedgemma cups.
Lunularia cruciata grows large, dichotomously branched greenthalli with crescent shaped gemma cups containing disc-likegemmae.[6] This is a unique morphological characteristic not possessed by other thalloid liverworts. Its thallus surface is shiny, faintly lined, and is dotted with tiny air pores. When dried the thallus turns yellowish in color and its margin rolls inward.[6]
As in other liverworts, the main plant body orthallus is ahaploidgametophyte. Theantheridia ofL. cruciata develops in early spring, thearchegonia develops in spring and sporophytes develop in late summer.[7] However, records of sporophyte developments and sexual reproduction are rare and scattered. This was suspected to have been the result of the anthropogenic spreading of this species, causing a disjunctive distribution of antheridia and archegonia.[7] When reproducing sexually, the four archegonia is arranged in a cross-shaped head (hence the specific namecruciata) bearingdiploid sporophyte plantlets. When reproducing asexually, the disc-shaped gemmae are readily dislodged from the cups by splashes of rainwater. They can then quickly "take root" and start to grow in suitably damp places, which is why they are so successful in greenhouses.
Lunularia cruciata is distributed across the world, found in continents includingEurope,Australasia,Asia, theAmericas, andAfrica. It occurs commonly in western Europe, and is native to theMediterranean region, where the morphological forms from sexual reproduction are more frequently found there.[7] It is also common inCalifornia, where it now grows "wild", and is known as an introduced weed in gardens and greenhouses inAustralia.[8]Ella Orr Campbell believed thatL. cruciata was introduced intoNew Zealand sometime after 1867.[9] Thesporophytes ofL. cruciata are rare, but has been found in European regions, as well as inSouth Africa,Argentina, California,India,Japan and New Zealand.[7]
Lunularia cruciata grows in damp, shaded and disturbed habitats such as path and wall edges.[6] It can act as a nutrient indicator because it often grows in alkaline and eutrophic to highly eutrophic soil.[7] Other habitats includeloam, boulders, concrete, exposed tree roots, soil covered logs and in the gaps between sidewalk stones.[7]L. cruciata also grows as a horticultural weed in gardens, greenhouses and parks.[7][6]L. cruciata is sensitive to frost, and is often found near water, where its gemmae are washed ashore.[7]
Like many other liverwort species,L. cruciata produces a dihydrostilbenoid growth hormone,lunularic acid, that is reported to be a growth inhibitor of liverworts.[10]Cadmium in this liverwort also inhibits gemma germination and apical thallus growth, as well as altering cell andchloroplast structure.[11]Acetone extracts fromL. cruciata were tested and showed antibacterial properties, but had no effects against fungal activity.[12]