Carnivorous Plants near Mt. Lesueuer, Western Australia
Robert Gibson
On the weekend of September 16 and 17, 1995, I had the pleasure in participating in a vegetation survey on a farm near Mt. Lesueur, approximately 250 km north of Perth. During this survey a number of carnivorous plants were found, 13 species of Drosera and Byblis gigantea, which are described below.
Byblis gigantea
Byblis gigantea was found in two sites on the farm, both of which were on hillslopes growing in a soil derived from fine, possibly windblown, quartz sand and fragments of massive lateritic ironstone. The plants were found on disturbed ground, along firebreaks, and would have undoubtedly have occurred in the adjacent undisturbed low heathy vegetation known as ‘kwongan’.
At least ten mature plants were found at each site, and were in active growth, some of which had commenced flowering. The plants grew to 30cm tall, had one to three stems each, with erect linear leaves to 22cm long. At the lower part of the stem the leavers were close together, with 1 to 3 mm internodes. The more recent growth had internodes 1 to 2 cm apart and single, auxiliary flowers, the latter though were not present in the lowest 2cm of more rapid stem elongation. The pedicels were just shorter than the leaves and held a single, outfacing iridescent purple petalled flowers to 3cm diameter. A single seedling, with leaves to 5cm long and a poorly developed stem was found at one site.
The plants were fully bedewed and had caught a range of flying insects, including aphids, midges and a smaller number of bush flies. Most plants had at least two lime-green Drosera bugs on them which moved readily over the bedewed plants. No insects were seen visiting the open flowers.
These plants are part of the northern population of this species which differs from plants around Perth. These plants are generally smaller; have shorter leaves; grow in well drained soil on hillslopes; produce stems with less branching and fewer plants from the root-system of established plants and had petals of the same colour throughout. They differ in choice of habitat form the southern population which prefer to grow in deep sand on the edge of swamps, and in the flower colour which includes a flattened, darker purple base on the inside of each petal
Drosera barbigera
Large numbers of the attractive and robust pygmy sundew, Drosera barbigera, were seen on the top and flanks of one of the laterite hills on the property. The plants grew in ironstone soil, with variable amounts of sand, often in colonies of a few tens to hundreds of plants. The semi-erect rosettes grew to 3cm diameter, on the end of often-prostrate stems to 5cm long. Many plants were in flower, with one to two scapes each., These grew to 10 cm long and had a tight cluster of flowers with conspicuously hairy sepals. The vibrant orange petalled flowers, to 1cm diameter, were open under sunny conditions, or when in the protection of adjacent low shrubs under cloudy conditions. The petals had a dark red base which was adjacent to the similarly coloured ovary and its three threadlike styles. The anthers produced pale yellow pollen which stood out against this dark coloured zone. A brown beetle was seen visiting one flower and may act as a pollinator.
Drosera enneaba
Large colonies of the pygmy sundew, Drosera enneaba, grew in sandy soil on the flanks of laterite plateaus. The glistening rosettes, to 2cm diameter, were seen in abundance on the fire trails. The orbicular red tentacled lamina occurred on the end of straight-sided petioles and formed a flat rosette. Many plants were in flower and had one, rarely two scapes , to 15 cm tall. The sweetly scented flowers had all white-petals, save for the distinct red dot near the ovary
Drosera erythrorhiza ssp ?magna
Scattered colonies of closely spaced rosettes of a taxon of the tuberous sundew, Drosera erythrorhiza, were seen throughout the farm in areas of deep sand, and on the edge and top of laterite plateaus. The rosettes were generally very red, with up to 8 leaves and were up to 8cm diameter, although most were smaller. Some plants were still bedewed although many were now starting to die down. A few still had the remains of scapes, which had already shed their seed. From the number of leaves and the size of the plants they were tentatively ascribed to subspecies magna, although some colonies could have been subspecies erythrorhiza. The close spaced colonies of these plants indicates either that some asexual reproduction occurs or the seed generally does not travel far from the parent plant. The identity of this taxon could be confirmed by looking at the root system and in checking the timing of flowering with respect to maturation of the rosette. Whatever its identity it is a large and beautiful variant in leaf.
Drosera gigantea
Scattered plants of the erect growing tuberous Drosera gigantea were seen in two locations in the area. One was in a creek bed, in water to 10 cm deep, and adjacent parts of the bank where plants to 40cm tall were seen. These were in bud, with many branches, few of which had mature leaves. The second site was in deep sand several hundred metres from the nearest creek bed. Some of these plants were already in flower although many had started to go dormant with the shrivelled remains of aborted inflorescences. At the second site a few plants had deep red stems.
Drosera glanduligera
Flowering rosettes of the annual Drosera glanduligera were found in the area. They grew on the south facing slope of a laterite plateau, in sandy soil, in the company of D. marchantii ssp prophylla, and also grew in deep sand, with D. gigantea. The golden green rosettes grew to 3 cm diameter and had up to 3 scapes.
Drosera macrantha ssp macrantha
Scattered plants of the climbing tuberous sundew, Drosera macrantha ssp macrantha ,were found growing on laterite plateaus and also in deep sand. At the time of the visit the species had finished flowering and was starting to die down. This species was recognised by the relatively thick (2 - 3 mm diameter) stem, generally golden green colour, presence of glandular hairs on the upper part of the stem, including the inflorescence, and pedicels of the leaves, and circular, and down-facing leaves borne in threes, the central one of which had a long pedicel, to ca. 8cm long .
Drosera marchantii ssp prophylla
Scattered plants of the erect growing tuberous sundew, Drosera marchantii ssp. prophylla, were found growing on the flanks of laterite hills growing in a sand and laterite soil. The plants had finished flowering at the time of the visit, a few of which had already shed their seed. The golden green plants grew to ca. 25 cm tall, had a conspicuously inflated base which was covered by a numerous linear scale-like leaves, had few flowered inflorescences with flowers held on relatively long scapes, had leaves held singularly on the stem, and which often grew in small groups of up to 4 plants probably derived from natural division of the tuber.
Drosera menziesii ssp menziesii
A few plants of the slender climbing tuberous sundew, Drosera menziesii ssp. menziesii, were found near the creek on the property, and were also found in greater abundance in deep sand near Moore River. The plants were in flower at the time of the visit and had red, slender glabrous climbing stems to 30 cm tall. The round leaves were borne in threes up the stem and the pedicels were generally less than 2 cm long. The deep pink petalled flowers were fragrant and had hairy sepals.
Drosera menziesii ssp thysanosepala
A large number of the slender climbing tuberous sundew, Drosera menziesii ssp thysanosepala, were found growing in kwongan vegetation on the upper parts of laterite plateaus in sandy soil with ironstone. The plants were very red in colour, lacked hairs, except for the margins of the sepals, and had leaves in threes alternating up the stem. The pale pink flowers were open at the time of our visit, even under overcast conditions, were sweet smelling and almost circular in outline. I observed a hover fly visiting one flower, perhaps feeding on pollen, and which may act as a pollinator.
Drosera miniata
Abundant plants of the pygmy sundew, Drosera miniata, were found on the upper portions of the laterite plateaus. They grew in soil composed on ironstone with a variable content of sand, in the sandier soils they sometimes grew with D. enneaba. The flat rosettes grew to 1.5 cm diameter, which were often hard to see. The most conspicuous feature of this species were the open flowers, to ca. 8mm diameter, which had iridescent orange petals with dark red, almost black veins radiating out from the black ovary, the later was surmounted by three thread-like styles. The dark red coloured stamens were generally not a conspicuous feature of the open flowers.
Drosera miniata often grew with D. barbigera and the two were often flowering together. It was interesting to note that the flowers of both species were very similar in appearance and size - orange with a dark red centre, yet there were no signs of hybrids between these species.
Drosera pallida
A few plants of the climbing tuberous sundew, Drosera pallida, were found growing near the top of a some laterite hills. This species had finished flowering and was starting to die down at the time of out visit but was identified from the other climbing sundews by the following; glabrous stem, usually 2mm diameter, and sepals; general lime green colour of the plants and rounded, down facing lamina, borne in threes with pedicels often 2 to 4 cm long.
Drosera stolonifera ssp humilis
A few plants of the tuberous sundew, Drosera stolonifera ssp. humilis were found at the farm. They grew in sandy soil on the mid slope of a laterite hill and on flat ground near a creek. These many branched plants had stems to ca. 12 cm long and no signs of the remains of inflorescences. The whorled leaves had petioles which were circular in cross section and triangular lamina which the upper corners folded up towards each other. The slender stolon grew across the ground for up to 3cm after it had emerged from above the tuber.
D. stolonifera ssp porrecta
An abundance of the tuberous sundew, Drosera stolonifera ssp porrecta grew on the property on the flanks and upper portions of the laterite hills. The plants emerged vertically above the tuber and immediately formed two rosettes of short petioled leaves. The plants varied in the amount of branching which occurred above the two basal rosettes. Plants produced between one and ca. five stems, which grew erect, up to 20 cm long. The mature leaves were borne in whorls , had a furrowed petiole and were triangular in outline with the upper corners folded back so that they were almost in contact and which resulted in an almost circular outline to the leafblade. Many of the branching plants had flowered, and had now shed most of their seed. The inflorescence emerged from the top of the upper basal rosette at the base of the branches. Most plants grew singularly although a few had divided once.
In addition to the carnivorous plants mentioned above flowering plants of the erect tuberous sundew, Drosera microphylla had been seen on laterite hills on the property in early winter. The plants had orange petals (M. Hislop, pers. Comm., 1995).
The area near Mt. Lesueuer has a remarkably diverse flora, as indicated by the range of carnivorous plants which were seen there. It is a botanist’s delight to spend time in the area.Acknowledgements:
I wish to thank the Murdoch Branch of the Wildflower Society of Western Australia for the opportunity to be involved in this vegetation survey, and for the owners of the properties visited for granting access.
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