Byblis (plant): Difference between revisions

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 a [[mucilage|mucilaginous]] substance from their tip. These serve to attract small [[insect]]s, which upon touching the sticky secretions are ensnared. Unless they are strong enough to escape, the insect prey either die of exhaustion or [[asphyxiate]] as the mucilage envelops them and clogs their [[Spiracle (arthropods)|spiracles]]. Unlike the sundews, however, ''Byblis'' can move neither their tentacles nor the leaves themselves to aid trapping or digestion. As a result, they are grouped among the "passive flypaper traps" along with ''[[Pinguicula]]'', ''[[Drosophyllum]]'', ''[[Roridula]]'', ''[[Stylidium]]'' and ''[[Triphyophyllum peltatum]]''.

Fertilized flowers mature to form an egg-shaped, two-parted seed capsule. As the seed capsule dries out it cracks open (dehisces), dropping the [[seed]] on the ground. The black seeds are generally round and often bear webbed surface markings, although those of ''B. lamellata'' are strongly ridged.<ref> [https://web.archive.org/web/20060629132453/http://seeds.carnivoren.org/images/156.jpg {{Bare URL image|date=August 2024}}]</ref>. The [[germination]] of many species is brought on by [[bush fire]]s after the dry period; [[wikt:pyrogenic|pyrogenic]] chemicals in the smoke are responsible for triggering germination.

The status of the genus as a truly [[carnivorous plant]] has been repeatedly put into question. In their natural habitat, all species have been observed playing host to live [[Hemiptera|bug]]s of the genus ''[[Setocoris]]'', which nourished themselves by eating prey caught by the plants. Following this discovery it was assumed that, as with the genus ''[[Roridula]]'', the plants do not actually digest their prey themselves, rather relying on the bugs to do that. The plants, it was reasoned, benefited by absorbing nutrients from the excrements of the bugs, either through their leaves or through the ground. An indirect digestion of these nutrients by a [[chitinase]] producing [[fungus]] was even proposed. It was not until 2005 that direct digestion of insect prey by enzymes secreted by the sessile glands of ''B. filifolia'' was proven.<ref>{{cite journal|last1=Hartmeyer, |last2=Irmgard und |last3=Siegfried: |title=''Byblis filifolia'' als echte Karnivore rehabilitiert'', |journal=Das Taublatt (GFP), |volume=53, 4-5, |issue=4–5|year=2005}}</ref> Soon thereafter similar results were found with ''B. liniflora''. These results clearly place this genus among the true carnivorous plants.

The four species of this complex, ''B. liniflora'', ''B. rorida'', ''B. filifolia'' and ''B. aquatica'', are [[annual plant|annual]] [[herbaceous]] plants that reach a height of {{convertcvt|15|-|50|cm|in|abbr=on}} and a maximum leaf length of {{convertcvt|4|-|15|cm|in|abbr=on}}. 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 original [[haploid]] [[chromosome]] count of this complex is x=8. The [[diploid]] number is therefore 2n=16, whereas the [[polyploid|tetraploid]] species ''B. liniflora'' is 2n=32.

The remaining two species, ''B. lamellata'' und ''B. gigantea'', make up what is known as the ''B. gigantea'' complex. These perennial species are both [[endemism|endemic]] to [[Southwest Australia]], and reach heights of {{convertcvt|45|-|70|cm|in|abbr=on}}. Unlike the annual members of the ''B. liniflora'' complex, these species survive the dry season by dying back to an underground [[rhizome]], out of which they emerge come fall. The leaves of this complex can reach {{convert|20|cm|in|abbr=on}} in length. The base chromosome count of the complex is x=9; since both species are diploid, their chromosome count is 2n=18.