Finlayson's Sundew

Drosera finlaysoniana is a tall annual sundew of Australia and parts of East and Southeast Asia, with long, thread-like sticky leaves on stems up to about 20 inches (50 cm). Long treated as part of Drosera indica, it was recognized again as a separate species in 2013. It grows fast, flowers and dies in a single season.

D. finlaysoniana is an upright herb with simple, often lax, hairy stems up to 50 cm (20 in) tall. Linear leaves, mostly 5-15 cm (2-6 in) long, are scattered along the stem and narrow gradually to a short, hairless base. The ICPS notes that, unlike D. indica, it has no distinct petiole, so the long-stalked glands cover almost the whole leaf. Flowers 15-25 mm across, pink, orange or white, are borne on inflorescences of 3 to 25 flowers.

It belongs to Drosera section Arachnopus, the D. indica complex, all of whose members are annuals. The complex was treated as a single variable species for most of the 20th century; in 2013 Russell Barrett and Allen Lowrie resurrected D. finlaysoniana, distinguishing it by glandular hairs that do not reach the stem at the leaf base, few simple hairs among the glands, normal (not hooded) anthers, and relatively small seeds with a distinctly net-patterned surface.

Regione nativa: Australia (Queensland, New South Wales, Victoria, Western Australia) and parts of East and Southeast Asia, including Vietnam, Taiwan and Hainan

Zone climatiche: Tropical and subtropical with wet and dry seasons; warm indoors elsewhere

Species of the D. indica complex grow in tropical and subtropical places with distinct wet and dry seasons, along ephemeral creeks on sandy soil and in seasonal swamps; their seeds sprout as the rains begin. In New South Wales D. finlaysoniana grows in seasonally damp herbfields and along streams and flowers in winter. It is more common in northern Australia; in the south it has been recorded inland in eucalyptus woodlands subject to flooding. A 2021 revision of its range found that, contrary to some published references, it does not occur in India, Laos, Cambodia or the Philippines.

Dimensioni mature: Stems up to 20 in (50 cm); leaves about 2-6 in (5-15 cm) long

Tasso di crescita: Fast

Tipo di trappola: Flypaper Trap

Long-stalked glands along the leaves secrete drops of sticky mucilage that hold small insects. Because the plant has no distinct petiole, the glands cover almost the whole length of each leaf. Prey held in the mucilage are digested by the glands. Only feed leaves that are covered in dew.

It is a strict annual and dies after setting seed, so growers must collect seed every year.
It has been reported never to reproduce from root or leaf cuttings.
Most, if not all, 'Drosera indica' seed sold by the ICPS Seed Bank turned out to be D. finlaysoniana.
At least 11 species are now recognized in the D. indica complex, where there were once one or two.
The epithet honours George Finlayson, the medical officer who first collected it, in Vietnam.

The plant is named for George Finlayson, the medical officer on the East India Company's mission to Cochinchina in 1821-1822, who first collected it at Turon Bay, now Da Nang Bay in Vietnam. Nathaniel Wallich gave the name to a specimen in his catalogue of the Company's herbarium, but without a description, and George Arnott Walker Arnott provided a brief formal description in the 1830s, noting that it was much larger than D. indica and different in habit.

In his 1906 monograph of the Droseraceae, Ludwig Diels lumped all similar plants under D. indica, and the name D. finlaysoniana fell out of use for about a century. In 2013 Russell Barrett and Allen Lowrie, and Lowrie's work on the carnivorous plants of Australia, resurrected it along with several other species of the complex. In 2021 Thilo Krueger and Andreas Fleischmann chose a lectotype for the name and amended its known range.

1. Drosera finlaysoniana, Wikipedia
2. Growing Drosera indica complex species, International Carnivorous Plant Society
3. The Drosera indica complex, International Carnivorous Plant Society
4. Drosera finlaysoniana, PlantNET (NSW Flora Online), Royal Botanic Garden Sydney
5. Krueger, T. & Fleischmann, A. (2021) A new species of Drosera section Arachnopus from the western Kimberley, Australia, and amendments to the range and circumscription of Drosera finlaysoniana. Phytotaxa 501(1): 56-84