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| Byblis | |
|---|---|
 | |
| Byblis liniflora | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Lamiales |
| Family: | Byblidaceae Domin[1] |
| Genus: | Byblis Salisb. |
Byblis (/ˈbɪblɪs/BIB-liss) is agenus ofcarnivorous plants, sometimes termed therainbow plants for the attractive appearance of theirmucilage-coveredleaves in bright sunshine. Native toAustralia andNew Guinea,[2] it is the only genus in the familyByblidaceae. The first species in the genus was described by the English botanistRichard Anthony Salisbury in 1808. Eight species are now recognised.
Byblis species look very similar toDrosera andDrosophyllum, but are distinguished by theirzygomorphicflowers, with five curvedstamens off to one side of thepistil. These genera are in fact not closely related; modern classifications placeByblis in theLamiales, while thesundews andDrosophyllum are now placed in theCaryophyllales.
All species of the genus form upright growth supported by a weak, fibrous root system. The genus can be divided into two groups or "complexes": TheB. liniflora complex and theB. gigantea complex.
The leaves of all species are round in cross section and highly elongated, tapering at the end. The surface of the leaves is densely studded with glandular hairs which secrete amucilaginous substance from their tip. These serve to attract smallinsects, which upon touching the sticky secretions are ensnared. Unless they are strong enough to escape, the insect prey either die of exhaustion orasphyxiate as the mucilage envelops them and clogs theirspiracles.
Along with the stalked mucilaginous glands, the leaves are also equipped withsessile glands, which assumedly are responsible for the secretion of the digestive juices. Sessile glands are five to ten times as numerous as the stalked glands.
Byblis were previously grouped among the 'passive flypaper traps' along withPinguicula,Drosophyllum,Roridula,Stylidium andTriphyophyllum peltatum as the plants were believed to be capable of moving neither their leaves nor tentacles to aid in prey capture or digestion. However, research in 2019 showed that the tentacles ofByblis liniflora collapse following exposure to food, bringing the prey item into contact with the sessile digestive glands.[3] The same behaviour was later observed inB. gigantea.[4]
Flowers in this genus are borne singly at the end of unbranching, leaf-likeinflorescences which emerge from the leaf axils. The five-petaled flowers are generally purple to pale violet, thoughB. gigantea andB. filifolia can sometimes produce white flowers. Except for the self-fertileB. liniflora, all species requirepollen from other individuals forfertilization. The pollen release ofB. gigantea andB. lamellata is only triggered by theresonance frequency of the wings of a landing pollinator, helping ensure cross-pollination with other individuals. The flowers ofByblis start to bloom in early spring and last until late summer.
Fertilized flowers mature to form an egg-shaped, two-parted seed capsule. As the seed capsule dries out it cracks open (dehisces), dropping theseed on the ground. The black seeds are generally round and often bear webbed surface markings, although those ofB. lamellata are strongly ridged.[5] Thegermination of many species is brought on bybush fires after the dry period;pyrogenic chemicals in the smoke are responsible for triggering germination.
AllByblis species are native toAustralia.B. gigantea andB. lamellata areendemic to thePerth region of southwest Australia, while the species making up theB. liniflora complex are found only in north Australia. The exception here isB. liniflora itself, whose distribution extends into southernIndonesia andPapua New Guinea.
Like manycarnivorous plants,Byblis species usually grow inbogs andmarshes. They generally prefer seasonally wet sandy soil in partial or direct sunlight with temperatures between ~ 5–40 °C (41–104 °F).
As native plants of Australia, allByblis species are protected. Until the year 2000, they were also given international protection underCITES appendix II, but were removed from the list when Australia entered the CITES agreement. Since then trade of the genus has been unregulated outside of Australia. However, due to the sensitivity of the plant, interest in the genus has been restricted to a small portion of the carnivorous plant hobbyist community. The majority of plant material sold today is produced in cultivation, with the annualB. filifolia andB. liniflora being the most common. Most of the other species must be grown from seed, which is often collected from the wild for this purpose.
The West Australian speciesB. gigantea undB. lamellata are being threatened by habitat destruction forurban sprawl from cities such asPerth. Particularly damaging is the draining of wet habitats to produce arable land.B. gigantea is on theInternational Union for Conservation of Nature'sRed List of Threatened Species and is considered critically endangered.
In their natural habitat, all species of Byblis have been observed playing host to livebugs of the genusSetocoris, which nourish themselves by eating prey caught by the plants. In 2005, direct digestion of insect prey by enzymes secreted by the sessile glands ofB. filifolia and other members of this genus was confirmed.[6] Soon thereafter similar results were found withB. liniflora.
Molecular genetics studies have placed the genus in the orderLamiales. While its placement within the order is still unclear, it is closely related toMartyniaceae,Lentibulariaceae as well asGesneriaceae.
For a time, thegenusRoridula was also assigned to the family Byblidaceae. Since that time, however, it has been placed into its own family,Roridulaceae.
Traditionally the genus was divided into only two species, namelyB. gigantea andB. liniflora. Further species were described in the 1980s, particularly through the work of the Australian botanistAllen Lowrie. Eight species are currently recognised:[7]
The four species of this complex,B. liniflora,B. rorida,B. filifolia andB. aquatica, areannualherbaceous plants that reach a height of 15–50 cm (5.9–19.7 in) and a maximum leaf length of 4–15 cm (1.6–5.9 in). These species grow from seedlings to flowering plants in only a few months, setting seed and dying with the onset of the dry season. The originalhaploidchromosome count of this complex is x=8. Thediploid number is therefore 2n=16, whereas thetetraploid speciesB. liniflora is 2n=32.
The remaining two species,B. lamellata undB. gigantea, make up what is known as theB. gigantea complex. These perennial species are bothendemic toSouthwest Australia, and reach heights of 45–70 cm (18–28 in). Unlike the annual members of theB. liniflora complex, these species survive the dry season by dying back to an undergroundrhizome, out of which they emerge come fall. The leaves of this complex can reach 20 cm (7.9 in) in length. The base chromosome count of the complex is x=9; since both species are diploid, their chromosome count is 2n=18.
In the year 2004 a single fossil of a seed, resembling that of members of the modern dayB. liniflora complex, was discovered in south Australia dating from the middle of theEocene epoch. The species was assigned to the Byblidaceae as aparataxon of the genus.[8] The sole specimen was unfortunately destroyed in a lab accident shortly after being photographed.[8][9]
The Latin generic name "Byblis" originates from a goddess fromGreek mythology, of whomOvid wrote in hisMetamorphoses (IX, l. 454–664).Byblis, niece ofApollo, fell deeply in love with her twin brotherCaunus. At his rejection of her advances, she let forth an endless stream of glistening tears, eventually literally transforming into a spring. The droplets lining the leaves of theByblis are said to resemble those tears.
The English vernacular name - "rainbow plants" - also denotes the mucilaginous droplets which, under the right lighting conditions and viewing angle, sparkle in a rainbow of colors.
