Elaeocarpus angustifolius

It is an evergreen tree that grows quickly. The tree starts bearing fruit in three to four years.

The blue-coloured drupes of the tree contain large stones or pits, which are covered by an outer husk of fruit flesh. This blue colour is not derived from a pigment, but is caused by structural colouration.[12] The fruit weigh 7g on average, but range from 10 to 4g.[5] The stone at the centre of the fruit, technically a pyrena, is typically divided into multiple segments, which are locules, each usually bearing a seed.

No infraspecific forms are recognised. Populations in the periphery of the distribution exhibit a range of morphological characters which do not betray much biogeographical structuring, i.e. individuals can be found in New South Wales which may look almost identical to individuals in Malaysia or Fiji. However, in the centre of the distribution, the islands of Indonesia and in the Malay Peninsula, there are a number of confusingly divergent populations. In general, populations in this area can be divided into two main groups, larger leafed and flowered, and smaller leafed and flowered.[13]

A long history of use by man may have confused the issue further. It is possible the long-distance trade has mixed lineages, or influenced the distribution of specific types. The species is often cultivated as an urban street tree in Indonesia and Malaysia. It appears that the larger leafed form is more often selected for planting as a street tree here. This appears to already be the case on Java over a century ago, based on the collection notes accompanying herbarium specimens.[13]

A closer look at the stones used in classic mala garlands also reveals some interesting issues. It is the smaller stones which are traditionally worth the most, and many of the stones in the garlands are only 7mm in diameter, while known stones in museums collected by botanical collectors are all larger, 10mm and up. Not only that, special powers are ascribed to stones with more than the usual five facets, with those having more facets commanding a higher price. Prayer beads with up to 20 facets are known, but botanists have always collected ones with 5-7 facets, rarely 4 or 8. The small size may be due to a special cultivation technique (see section on Uses below) or an as yet unknown race or species, and it is possible there has been some limited selection by people involved in the trade -it is possible that there are, or once were, special cultivars grown for their superior stones.[13] A study of the fruit and stones in Sri Lanka found that variation in characteristics such as size and colour were highly influenced by the individual trees, as opposed to season or location. The authors opine that it is indeed possible that specific individual trees are cultivated for their fruit and stone qualities.[5]

It is a widespread and variable species, and many regional populations of E. angustifolius were considered to be different species in the past, but these are at present all considered the same species. An exception is the taxon E. grandis, although it cannot reliably be told apart from the E. angustifolius and was considered the same species by the last Elaeocarpus expert taxonomist,[11] it remains recognised in parts of Australia: plants in Queensland and New South Wales are considered E. grandis, those found growing elsewhere are E. angustifolius.[6][14] A 2013 PhD thesis by Yumiko Baba which compared a number of genetic sequences of different taxa found that E. grandis was indistinguishable from E. angustifolius in most studied sequences, but that in one sequence with more variety, her two E. grandis samples (one from Hawaii as E. sphaericus) were found to be within the diversity of E. angustifolius, with the two samples in fact more divergent from each other than from other samples within the E. angustifolius synonymy.[15]

E. grandis/angustifolius can, however, be told apart from other species of Elaeocarpus by having petals much divided at the apex; small, round fruit; 5-7 locules per stone; straight embryos; and glabrous leaves with even and fine serrations along their margins.[11] The most similar species in Northern Territory is E. arnhemicus; this species has leaves which are less long and more wide, stamens without bristles, and fruit which are ellipsoid in shape as opposed to round.[10]

Overal, Coode found E. ptilanthus to be the most similar species, and very difficult to tell apart without the fruit. Whereas E. angustifolius is largely a lowland species, E. ptilanthus is found in highlands and cloud forests. Coode notes that the crowns are different, that of E. ptilanthus being dark, dense and umbrella-like, as opposed to light and spreading. The leaves are leathery, darker and shinier on top. The most important difference is seen in the fruit; E. ptilanthus has twice-as-large fruit with fibrous flesh, E. angustifolius is more juicy. The stone is very different in E. ptilanthus, the ornamentation having developed into numerous holes and arches, through which the strong fibres run, making cleaning a stone difficult. These arches are usually flattened and long, and curve towards the apex of the stone. The stone is also shaped differently, it is ellipsoid or ovoid, not round.[13] A study comparing a number of gene sequences, however, found that a E. ptilanthus sample was largely indistinguishable from E. angustifolius, with the exception of one more variable sequence, where it was nested within different E. angustifolius samples.[15]

Other nations in Europe were beginning to build empires of their own, and where their fleets went, their botanists soon followed. As such the species was described numerous times throughout its vast distribution. The first (true) synonym, Elaeocarpus ganitrus, was coined in 1814 by the superintendent of the Calcutta Botanical Garden, William Roxburgh, in a simple list of names of he intended to give to plants found growing in the garden, titled Hortus Bengalensis. Because Roxburgh did not add any descriptions to this bare list, it is impossible to know what he was talking about. These names should thus all have been considered to be invalid nomina nuda, and should have been ignored,[21][26] but at least as far as this species is concerned the 1832 version of the posthumous publication of Roxburgh's manuscript for a Flora Indica validated this name,[21][27] i.e. E. ganitrus Roxb. ex. Roxb.. Nonetheless, it was generally rendered E. ganitrus Roxb. for most of the 19th century and later.[27][28][29]

Around the turn of the century the editors of the Index Kewensis had begun to realise that many old names from taxonomists in other European countries had not been registered, and many of the names of certain British scientists were not actually validly published, such as those of Roxburgh. In 1925 George Don's rather unscientific, but quite complete, 1831 gardening dictionary A General History of the Dichlamydeous Plants was rediscovered, and Roxburgh's name is now considered first validated in this work.[26][30] Of the nine Elaeocarpus names Roxburgh invented for the plants in the Calcutta garden, Don dismissed all of them as impossible to identify and probably just synonyms of species which had been described before by others, except for E. rugosus and E. ganitrus, for in the last case he recognised that the specific epithet meant it must be same plant as that of Rumphius almost two centuries earlier, supplied a summary description of it in his work and gave Ganitrus Ganitri as a synonym of Roxburgh's name.[31] Although the description is not in Latin and would also fail as a validation according to the rules of the ICBN, it is published before these rules were promulgated, and therefore still 'counts' as a valid publication. However, Tirel and Raynal pointed out in 1980 that Roxburgh's E. ganitrus is doubly invalid: although it was first published in 1814, it was only effectively published in 1831 with Don, six years after Blume's E. angustifolius, and the taxon which the name describes is ambiguous, because it is based on Gaertner.[21]

In the 1895 issue of the influential series Die natürlichen Pflanzenfamilien, Karl Moritz Schumann classified the genus Elaeocarpus into four sections. In section Ganitrus he describes E. angustifolius/ganitrus as the type species, which he considers to actually be a synonym of Gaertner's 1791 name Ganitrus sphaerica, which he recombined as E. sphaericus.[32] Schumann had written the work in or before 1890 already, and he was unaware at the time, like most other people, that Constantin von Ettingshausen had already recombined Ganitrus sphaerica two years before Die natürlichen Pflanzenfamilien had finally been published, in rather summary mention in a work on the fossil species of Tasmania.[33] E. sphaericus thus has two authors, rendered auctorum multorum in taxonomic jargon.[13] Because Ettingshausen had simply recombined the name, his version retains the synonym pro parte aspect of Gaertner's original name, but in Schumann's case he clearly identifies his name with the species E. angustifolius. Perhaps as a consequence of Die natürlichen Pflanzenfamilien, the species became known as E. sphaericus (Gaertn.) Schum. for almost the century in some regional floras,[11][21] i.e. Indonesia[34] and Australia.

In 1984 Coode regarded the taxon E. grandis as a synonym of E. angustifolius in his work Elaeocarpus in Australia and New Zealand, as it does not differ morphologically from the widespread and quite variable E. angustifolius.[11] This was never entered into databases of native plants in Queensland,[6] and in 2010 it was accepted as a valid species again by the Australian Plant Census.[2] It was thus entered into the 2014 Atlas of Living Australia, which led it to be recognised again by the Plants of the World Online website as of 2022, despite Rafaël Govaerts noting the synonymy in 2001.[35] Coode wrote again in 2010 in his study of E. angustifolius and its immediate relatives that as far as he can tell E. grandis is the same plant as the normal common and widespread form of E. angustifolius as found throughout the region. There is no difference between E. grandis from New South Wales and E. angustifolius from Malaysia, the Solomon Islands or the Philippines.[13]

E. hebridarum was described in 1941 by Reinhard Gustav Paul Knuth from specimens collected in Vanuatu, known at the time as the 'New Hebrides'.[36] In 1982 the French botanist Christiane Tirel moved it, as well as E. polyschistus and E. persicifolius which had both been described from New Caledonia, into synonymy with E. angustifolius.[37][38] E. macdonaldii is another possible synonym from Vanuatu described by Ferdinand von Mueller in 1893, which is/was missing from the Index Kewensis, but it may no longer be identifiable.[13]

It is classified in the Ganitrus group of the genus Elaeocarpus, along with E. altisectus, E. avium, E. buderi, E. dolichostylus, E. fulvus, E. kaniensis, E. ornatus, E. osiae, E. ptilanthus, E. ramiflorus and E. trichopetalus. It is the only species within the section which has spread beyond the Malay Archipelago.[13]

It occurs in the wild in the provinces of Yunnan, Guangxi[3][39] and Hainan.[39]

In the Indian subcontinent it grows in the Gangetic plain in the foothills of the Himalayas.[40] It grows on Sri Lanka, but it is not particularly common.[5]

It is native to New Caledonia,[37][38][41] Vanuatu,[36][37][38] and the Santa Cruz Islands.[38] It occurs on Fiji.[39]

In New Caledonia it occurs across Grande Terre (from Prony Bay to Poum), the Isle of Pines (île des Pins) and the Loyalty Islands (Lifou, Maré, Ouvéa). Note that E. angustifolius has often been imported from Australia to New Caledonia as an ornamental plant,[42] and according to the Australians these plants may technically actually be E. grandis, although this is a moot point if these two names are synonyms.

Specimens of E. angustifolius were planted in Oahu in the 1930s and have subsequently become naturalised in nearby forests.[43] Note that the plants in Hawaii were introduced from Australia[8] and may technically actually be E. grandis, although this is a moot point if these two names are synonyms.

The species is also reported to have been introduced from Australia and to invade intact and secondary forests in Samoa,[43] although it may actually be native,[13] and the report likely technically refers to E. grandis.[43]

Although some sources state the species is native to Guam,[39] this is a mistake. In the 1971 article The Flora of Guam, B. C. Stone recorded E. sphaericus (sensu Schum.) as being native to Guam. In a 1979 article in the same journal updating the wider flora of the region, A geographical checklist of the Micronesian Dicotyledonae, Fosberg et al. stated Stone's E. sphaericus (updated to E. angustifolius) was in fact E. joga. Confusingly, Fosberg et al. also state that E. grandis has been introduced to Palau.[44] Coode writes in 2010 that E. joga, and its pro parte synonym E. carolinensis, needs to be re-examined (it falls outside the purview of his paper) to see if it truly is an independent species and not a synonym, and to which section of the genus Elaeocarpus it belongs -like E. grandis, if it belongs to section Ganitrus this is a biogeographic oddity, all other species appear to have evolved in the Malay Archipelago.[13][44] If it is a synonym, this would expand the native distribution to throughout the Mariana Islands and in the nation of Palau.[44]

In the Northern Territory of Australia it is predominantly found on the Tiwi Islands and from Channel Point to Wadeye on the Northern Territory mainland where it grows to a height of about 25 m (82 ft).[9][6] It was also formerly thought to occur in Queensland, but the Australian Plant Census states that the trees from this area were in fact E. grandis, according to them the name E. angustifolius was misapplied pro parte.[2][45][46][47]

It has been introduced to West Africa, at least to Sierra Leone.[4]

In the USA the cultivar 'Prima Donna' has been available, it has pink flowers.[53] It may actually be E. reticulatus.

The Hindi vernacular name of both the tree and the stones is "rudraksha", from Sanskrit: rudrākṣa, a compound word consisting of the name Rudra ("Shiva") and akṣha ("teardrops" or "eyes").[54] The stones are widely used in Hinduism as prayer beads in the making of mala (garlands).[13]