Helicia

Helicia is a genus of 110 species of trees and shrubs, constituting part of the plant family Proteaceae. They grow naturally in rainforests throughout tropical South and Southeast Asia, including India, Sri Lanka, Indochina, Peninsular Malaysia to New Guinea and as far south as New South Wales.

Conservation

At global, national and regional government scales, many Helicia species have been threatened with extinction, as officially recognised by the International Union for Conservation of Nature (IUCN) and by continental, national and local governments. Seventeen species have official IUCN global conservation statuses of either "critically endangered", "endangered", "vulnerable" or "near threatened" (in terms of global extinction).

Naming and classification

In 1790, notable pioneer botanist João de Loureiro described this genus as Helicia in his publication Flora Cochinchinensis. The type species for the genus was Helicia cochinchinensis, the type specimen of which was collected in Cochinchina, Vietnam. The genus name derives from the Greek word "" (élix), which refers to the petals, now called tepals, spirally revolving or simply rolling or coiling up on themselves, at anthesis (the flowering time when the anthers open).

In 1831, botanist Nathaniel Wallich named Helicia robusta for a dried specimen of a cultivated plant in India, based on the specimen's earlier 1814 name Roupala robusta by William Roxburgh. Roxburgh's Calcutta botanic gardens cultivated the plant.

From the 1850s to the 1860s notable German–Australian botanist Ferdinand von Mueller formally described several new Australian species. In the late 1800s and early 1900s Frederick M. Bailey concentrated further on additional Queensland species, writing descriptions of them in numerous scientific papers.

In 1939, Hermann O. Sleumer described many additional Malesian species, especially in New Guinea. In 1955, he published a revision of the genus. In 1956, his treatment of the genus in Flora Malesiana was published.Template:Sfnp From 1969 to the late 1990s botanist Don B. Foreman, who was based in Papua New Guinea and Australia, collected numerous additional species, which he formally described before he wrote the comprehensive reviews and flora treatments for the two regions; notably in the authoritative Handbooks of the Flora of Papua New Guinea (1978–1995, to date 3 volumes), he wrote the chapters for Proteaceae and other families;Template:Sfnp and in the authoritative Flora of Australia (1981–, 60 volume series) he wrote the treatment of Helicia.

From the 1990s botanist Richard C. K. Chung, based in Malaysia, published new species formal descriptions and a revision of the 13 species occurring in Borneo. In total, approximately 100 species have been formally scientifically described.

Lawrie Johnson and Barbara G. Briggs grouped Helicia with Xylomelum in the subtribe Heliciinae, tribe Helicieae, and subfamily Grevilleoideae in their 1975 monograph "On the Proteaceae: the evolution and classification of a southern family". However, genetics studies showed these two to be relatively unrelated, instead finding the closest genetic correlations between Hollandaea and Helicia, and therefore classifying them both in the subtribe Heliciinae within the tribe Roupaleae.

Diversity and description

File:Helicia glabriflora Coffs Harbour Botanic Gardens.jpg

Helicia glabriflora from New South Wales, Australia

Helicia plants generally grow naturally as small trees, while some species grow as shrubs and some grow to medium-sized trees up to .Template:SfnpTemplate:Sfnp

They grow naturally across the Malesia region with the major centre of species diversity of about fifty species in New Guinea. They grow naturally in the south west Pacific ocean region, and in north and eastern Australia. They grow naturally across southern and eastern Asia, including Indonesia, Malaysia and another centre of species diversity of about twenty species in southern China, extending to parts of the Indian subcontinent, the Philippines, Taiwan, and southern Japan.Template:SfnpTemplate:Sfnp The plant family Proteaceae's 1,700 species (approximate) have their greatest diversity in the southern hemisphere and smaller centres of diversity including some Helicia, in the near northern hemisphere. The species diversity of the plant family Proteaceae decreases further northwards. H. cochinchinensis has the natural distribution reaching furthest north to Japan where it grows into trees in the mountains of warmer parts and where no other species nor other Proteaceae genera occur. The same Japanese name for this species, also means the whole genus and the entire Proteaceae plant family. In the New Guinea and southern China centres of species diversity, many species grow in forests, up to as tall as the sub-canopy, especially diverse in rainforests.Template:Sfnp In Australia, they are generally components of rainforests, and prefer richer soils, especially in the farthest south region of Helicia's global distribution, the Illawarra, New South Wales, south of Sydney, where only one species H. glabriflora occurs, preferring richer basalt soils.

Cultivation

In India and east Asia, Helicias have been cultivated in botanic gardens, from the 1800s. In Australia they have rarely been cultivated, and were thought to have little horticultural value. The rusty-coloured new growth is attractive on some species. In some of the better known Australian species, the flowers and fruit are generally not prominent, and plants can be slow growing. They are generally propagated by seed, the viability of which drops rapidly with time.

Species

(this list may have a small number of species missing, presently it has 99, out of the approximate total stated by sources of 110)

• Helicia acutifolia Template:AuTemplate:Sfnp – New Guinea – Globally Vulnerable
• Helicia affinis Template:AuTemplate:Sfnp – New Guinea
• Helicia albiflora Template:AuTemplate:Sfnp – New Guinea – Globally Near threatened
• Helicia amplifolia Template:AuTemplate:Sfnp – New Guinea – Globally Near threatened
• Helicia archboldiana Template:AuTemplate:Sfnp – New Guinea
• Helicia attenuata Template:Au – Borneo
• Helicia australasica Template:AuTemplate:Sfnp – New Guinea, Australia – Globally Vulnerable
• Helicia blakei Template:Au – Australia
• Helicia bullata Template:AuTemplate:Sfnp – New Guinea
• Helicia calocoma Template:AuTemplate:Sfnp – New Guinea – Globally Vulnerable
• Helicia cameronii Template:AuTemplate:Sfnp – New Guinea
• Helicia carrii Template:Au(Syn: H. brassii, H. divaricata Template:Au)Template:Sfnp – New Guinea
• Helicia celatus Template:Au – New Guinea
• Helicia ceylanica Template:Au – Sri Lanka endemic
• Helicia clivicola Template:Au – China region
• Helicia cochinchinensis Template:Au – China, Indochina, Taiwan, Japan
• Helicia coeruleopurpurea Template:AuTemplate:Sfnp – New Guinea
• Helicia commutata Template:AuTemplate:Sfnp – New Guinea
• Helicia dongxingensis Template:Au – China region
• Helicia excelsa Template:Au – Borneo
• Helicia falcata Template:Au – China region
• Helicia ferruginea Template:Au – Australia
• Helicia finisterrae Template:AuTemplate:Sfnp – New Guinea
• Helicia forbesiana Template:AuTemplate:Sfnp – New Guinea
• Helicia formosana Template:Au – China region
• Helicia fragilis Template:Au – New Guinea
• Helicia fuscotomentosa Template:Au – Borneo endemic
• Helicia glabriflora Template:Au – eastern Australia
• Helicia graciliflora Template:Au – Philippines endemic
• Helicia grandifolia Template:Au – Vietnam endemic – Globally Vulnerable
• Helicia grandis Template:Au – China region
• Helicia grayi Template:Au – Australia
• Helicia hainanensis Template:Au – China region
• Helicia hypoglauca Template:AuTemplate:Sfnp – New Guinea, New Britain
• Helicia insculpta Template:AuTemplate:Sfnp – New Guinea
• Helicia insularis Template:AuTemplate:Sfnp – New Guinea – Globally Endangered
• Helicia islandica Template:Au – New Guinea
• Helicia kwangtungensis Template:Au – China region
• Helicia laiagamensis Template:AuTemplate:Sfnp – New Guinea
• Helicia lamingtoniana Template:Au – Australia
• Helicia latifolia Template:AuTemplate:Sfnp – New Guinea – Globally Near threatened
• Helicia lauterbachiana Template:Au(Syn: H. grandifolia Template:Au)Template:Sfnp – New Guinea
• Helicia ledermannii Template:AuTemplate:Sfnp – New Guinea
• Helicia lewisensis Template:Au – NE Queensland, Australia
• Helicia longespicata Template:AuTemplate:Sfnp – New Guinea
• Helicia longipetiolata Template:Au – China region
• Helicia loranthoides Template:Au – Philippines endemic
• Helicia macrostachya Template:AuTemplate:Sfnp – New Guinea
• Helicia maxwelliana Template:Au – Borneo: Sabah endemic, rare
• Helicia microneura Template:AuTemplate:Sfnp (Syn: H. arguta Template:Au) – New Guinea
• Helicia microphylla Template:AuTemplate:Sfnp – New Guinea
• Helicia moluccana Template:Au – MoluccasTemplate:Sfnp
• Helicia neglecta Template:AuTemplate:Sfnp – New Guinea Bismarck Archipelago endemic: New Britain, New Ireland – Globally Vulnerable
• Helicia nilagirica Template:Au – Southeast Asia, Yunnan, India, Nepal
• Helicia nortoniana Template:Au – Australia
• Helicia obovata Template:Au – Java, Borneo
• Helicia obovatifolia Template:Au – China region

• var. mixta Template:Au – China region
• var. obovatifolia – China region

• Helicia obtusata Template:Au(Syn: H. clemensiae Template:Au)Template:Sfnp – New Guinea
• Helicia odorata Template:AuTemplate:Sfnp – New Guinea
• Helicia olivacea Template:AuTemplate:Sfnp – New Guinea
• Helicia oreadum Template:AuTemplate:Sfnp – New Guinea
• Helicia pallescens Template:AuTemplate:Sfnp – New Guinea
• Helicia paucinervia Template:Au – Philippines endemic
• Helicia peekelii Template:AuTemplate:Sfnp – New Guinea Bismarck Archipelago: New Ireland endemic – Globally Vulnerable
• Helicia peltata Template:AuTemplate:Sfnp – New Guinea – Globally Critically endangered
• Helicia petiolaris Template:Au – Borneo
• Helicia platyphylla Template:AuTemplate:Sfnp – New Guinea
• Helicia polyosmoides Template:AuTemplate:Sfnp – New Guinea Bismarck Archipelago: Manus Island endemic – Globally Critically endangered
• Helicia pterygota Template:Au – Borneo: Sabah endemic, rare
• Helicia pyrrhobotrya Template:Au – China region
• Helicia recurva Template:Au – Queensland Australia
• Helicia rengetiensis Template:Au – China region
• Helicia retevenia Template:AuTemplate:Sfnp – New Guinea
• Helicia reticulata Template:Au – China region
• Helicia retusa Template:AuTemplate:Sfnp – New Guinea – Globally Vulnerable
• Helicia robusta Template:Au var. robusta – Malesia: Borneo, Philippines, India
• Helicia rostrata Template:AuTemplate:Sfnp – New Guinea – Globally Vulnerable
• Helicia rufescens Template:Au – Borneo, rare
• Helicia saruwagedica Template:AuTemplate:Sfnp – New Guinea
• Helicia saurauioides Template:AuTemplate:Sfnp – New Guinea
• Helicia schlechteri Template:AuTemplate:Sfnp – New Guinea
• Helicia sellae-montis Template:AuTemplate:SfnpTemplate:Sfnp – New Guinea
• Helicia serrata Template:Au var. serrata – Borneo
• Helicia sessilifolia Template:Au – Borneo: Sabah & Sarawak endemic, uncommon
• Helicia shweliensis Template:Au – China region – Globally Endangered
• Helicia silvicola Template:Au – China region
• Helicia sleumeri Template:Au – New Guinea
• Helicia stelechantha Template:AuTemplate:Sfnp – New Guinea
• Helicia subcordata Template:AuTemplate:Sfnp – New Guinea – Globally Critically endangered
• Helicia symplocoides Template:Au – Borneo endemic – Globally Vulnerable
• Helicia tibetensis Template:Au – China region
• Helicia torricellensis Template:AuTemplate:Sfnp – New Guinea
• Helicia tsaii Template:Au – China region
• Helicia uganensis Template:AuTemplate:Sfnp – New Guinea Bismarck Archipelago endemic: New Britain, New Ireland
• Helicia varoyenii Template:Au – New Guinea
• Helicia versteeghii Template:Au – New Guinea
• Helicia vestita Template:Au

• var. longipes Template:Au – China region
• var. vestita – China region incl. Thailand

• Helicia wollastonii Template:AuTemplate:Sfnp – New Guinea
• Helicia yangchunensis Template:Au – China region