Academic literature on the topic 'Byblis gigantea'

Cytological studies carried out on the six species of Byblis (Byblidaceae) support the recent separation of taxa from within the Byblis liniflora Salisb. complex, as well as confirming the previously reported numbers of 2n = 18 for B. gigantea s.str. and 2n = 32 for B. liniflora s.str. Byblis sp. nov. aff. gigantea also has a chromosome number of 2n = 18, whereas B. filifolia Planch., B. rorida Lowrie & Conran and B. aquatica Lowrie & Conran have counts of 2n = 16. This gives base counts of x = 8 for the B. liniflora complex and x = 9 for the B. gigantea complex, with B. liniflora as a tetraploid.

Carnivorous rainbow plants (Byblis, Byblidaceae, Lamiales) possess sticky flypaper traps for the capture, retention, and digestion of prey (mainly small insects). The trapping system is based on a multitude of millimeter-sized glandular trichomes (also termed stalked glands), which produce adhesive glue drops. For over a century, the trapping system of Byblis was considered passive, meaning that no plant movement is involved. Recently, a remarkable discovery was made: the stalked glands of Byblis are indeed capable of reacting to chemical (protein) stimuli with slow movement responses. This prompted us to investigate this phenomenon further with a series of experiments on the stimulation, kinematics, actuation, and functional morphology of the stalked glands of cultivated Byblis gigantea plants. Measured stalked gland lengths and densities on the trap leaves are similar to the data from the literature. Motion reactions could only be triggered with chemical stimuli, corroborating the prior study on the stalked gland sensitivity. Reaction time (i.e., time from stimulation until the onset of motion) and movement duration are temperature-dependent, which hints towards a tight physiological control of the involved processes. The stalked gland movement, which consist of a sequence of twisting and kinking motions, is rendered possible by the components of the stalk cell wall and is furthermore anatomically and mechanically predetermined by the orientation of cellulose microfibrils in the cell wall. Successive water displacement processes from the stalk cell into the basal cells actuate the movement. The same kinematics could be observed in stalked glands drying in air or submersed in a saturated salt solution. Stimulated and dried stalked glands as well as those from the hypertonic medium were capable of regaining their initial shape by rehydration in water. However, no glue production could be observed afterwards. The long-time overlooked chemonastic movements of stalked glands may help Byblis to retain and digest its prey; however, further research is needed to shed light on the ecological characteristics of the rainbow plant’s trapping system.

Byblis Salisb. is a small genus of carnivorous plants with adhesive traps in the Lamiales family Byblidaceae Domin. There are two perennial species (B. gigantea Lindl. and B. lamellata Conran & Lowrie) with restricted ranges in Western Australia, where they experience a Mediterranean climate. The critically endangered B gigantea is endemic to the Swan River drainage area, now entirely within the Perth metropolitan area, whilst B. lamellata is restricted to the coastal region North of Perth. The genus also contains six currently recognized annual species (B. aquatica Lowrie & Conran, B. filifolia Planch., B. guehoi Lowrie & Conran, B. liniflora Salisb., B. pilbarana Lowrie & Conran, and B. rorida Lowrie & Conran) which inhabit the tropical and semi-arid regions of Northern Australia. The genus also extends to the island of New Guinea (Lowrie 2013; McPherson 2010). All species are found in substrates which are very nutrient-poor (Lowrie 2013; McPherson 2010) and share habitats with representatives of other genera of carnivorous plants (particularly Drosera, but also Utricularia and Nepenthes). Although there are important morphological differences between the Byblis species, all share the same basic structure in that they produce stems from which radiate filiform leaves. Another feature common to all species is the ability to produce fast concentrated growth in response to seasonal rainfall. (Bourke, pers. comm.). It has been observed on many occasions that all Byblis species play host to Miridae bugs from the genus Setocoris (Bourke, pers. comm.). A mutualistic relationship has been proven to exist between another viscid plant genus Roridula and a different genus of the family Miridae, Pameridea (Anderson & Midgley 2003). A similar relationship is strongly suspected in Byblis (Lowrie 2013; Cross et al. 2018).

Byblis Salisb. is a highly understudied carnivorous genus currently consisting of eight recognized species – now with motile adhesive traps (Allan 2019 [p 51 this issue])). In particular, the carnivorous syndrome exhibited by the genus is imperfectly understood when compared to other carnivorous plant genera. The leaves, stems, pedicels, and sepals bear stalked glands and digestive glands. The stalked glands vary in length, even within individual plants, the longest stalks reaching 2.6 mm in length (McPherson 2010). Each stalked gland bears a droplet of mucilage, assumed to be sugar-based and water-soluble (Bauer et al. 2018), that is responsible for prey-capture. The far more numerous digestive glands sit in rows in longitudinal grooves on the epidermis (Lloyd 1942) (see Fig. 1) and are usually assumed to secrete digestive fluids in response to prey-capture, as well as to absorb the products of digestion (Cross et al. 2018). The stalked glands are capable of collapsing in response to detection of animal proteins, apparently due to a rapid loss of cell turgidity. In consequence, prey can be brought within the range of the secretions of the digestive glands.

The relationships of the Byblidaceae have been the subject of a number of recent molecular phylogenetic studies where their traditional relationships with the Roridulaceae and other members of the Rosidae have been overturned in favour of affinities with the Asteridae, in particular to the Lentibulariaceae in the Lamiales. Although the embryological relationships between these families were the subject of an earlier study, the data for the Byblidaceae were incomplete. The family has tetrasporangiate, bilocular anthers with a glandular bi-nucleate tapetum. Formation of the anther wall appears to be of the Dicotyledonous type, and the anthers have ephemeral middle layers and apical fibrous thickenings. Simultaneous microsporogenesis results in tetrahedral tetrads of bi-nucleate pollen grains. The ovules are anatropous, unitegmic and tenuinucellate. Megasporogenesis is direct from the archesporal cell, which in Byblis liniflora Salisb. divides to produce a linear tetrad from which a chalazal megaspore is derived (contrary to a report of a micropylar megaspore in B. gigantea Lindl.). Megagametogenesis conforms to the Polygonum type, and the antipodal cells are persistent. The endosperm is ab initio Cellular and there are well developed micropylar and chalazal haustoria. Embryogenesis appears to conform to the Onagrad type noted for several of the other members of the Lamiales s.l., including the Lentibulariaceae, to which the Byblidaceae have been related in recent molecular studies.

Abstract The Byblidaceae consist of five species of carnivorous plants belonging to the genus Byblis Salisb., mostly endemic to Australia. In northern Australia there are four herbaceous, annual species (Lowrie and Conran 1998), of which only B. liniflora Salish. has been examined for this work. In SW Australia and New Guinea is a short-lived perennial, moderately woody plant, B. gigantea Lindl., up to 0.5 m in height, also examined for this work. Both live in white sandy areas that are swampy in winter but dry in summer, where each year a proportion of plants succumbs to drought. B. gigantea is found growing on burnt areas, where it may occur in abundance. Both species have rhizomes from which the aerial parts arise.