Article

Shrubs

From Munshipedia, the MBRAS digital historical encyclopedia

Shrubs

Scope and Historical Definition

The term “shrub” in the botanical literature of the Straits Settlements and the Malay Peninsula, as it appears in the early twentieth-century taxonomic record, refers to a woody plant of limited stature—typically not exceeding a few metres in height—that branches from or near the ground and lacks a single dominant trunk. The two records examined here illustrate how the descriptor was applied in practice: Burkill characterises Plethiandra sahebii as a “shrub about a metre high” [1, p. 266], while Ridley describes Lasianthus barbellatus as a “3-foot shrub” [2, p. 187]. Both are small, multi-stemmed, woody plants, and both were described as new species from the region between 1907 and 1917. The records do not offer a formal taxonomic definition of the growth form, nor do they attempt to distinguish shrubs from small trees or large herbs; rather, the term functions as a practical descriptor of habit, applied by the describing botanist to convey the plant’s overall architecture to a reader who may never see the specimen.

The regional prevalence of shrubs in the lowland and montane forests of Borneo and the Malay Peninsula is implied by the frequency with which the descriptor appears in species accounts, but the records before us do not quantify this prevalence or discuss shrub-layer ecology as a discrete subject. What they do establish is that shrubs of modest size—ranging from roughly one metre to three feet—constitute a significant component of the flora described in the Society’s journal during this period, and that they attracted the attention of botanists working on both the Melastomataceae and the Rubiaceae, two families of considerable diversity in the region.

Morphology and Growth Form

The two species described in the records exemplify distinct morphological strategies among small woody plants of the region. Plethiandra sahebii, as known from a single living specimen in cultivation at the Singapore Botanic Gardens, is a glabrous shrub approximately one metre in height that branches dichotomously from four basal stems, ultimately producing sixteen leafing branches [1, pp. 266–267]. The branching pattern is regular: the terminal bud is arrested, and a pair of axillary buds grows into leafing branches, a process that repeats at each node. The stems are never exactly green; when young they are suffused with a dull claret colour, becoming livid brown, and eventually developing a greyish-brown cork layer with lenticels that cracks longitudinally [1, p. 267]. The leaves are sessile, large—attaining 30 cm in length by 12 cm in breadth—ovate, and rounded at the base [1, p. 267]. A notable feature is the plant’s cauliflorous habit: flowering begins in the axils of old leaves and continues from the axillary bud even after the leaf has fallen, apparently without limit of time, so that the plant flowers among its own adventitious roots [1, pp. 266–267].

Lasianthus barbellatus, by contrast, is described more briefly by Ridley as a three-foot shrub with glabrous branches and subcoriaceous leaves that are briefly acuminate and cuneate at the base, glabrous and shining above, and hairy on the major veins beneath, measuring 3.5 to 4.5 inches long and 1.5 inches wide [2, p. 187]. The note is accompanied by a plate showing a leaf and a group of flowers reduced to one-tenth scale [2, p. 187]. The brevity of Ridley’s account—characteristic of his rapid species descriptions—means that the growth form, branching pattern, and ecological context of L. barbellatus are not elaborated beyond the basic habit and leaf morphology.

The comparison between the two species highlights the range of structural variation within the shrub growth form as it was documented in this period: from the highly regular dichotomous architecture and cauliflorous flowering of Plethiandra to the more conventional branching and leaf arrangement of Lasianthus.

Taxonomic Context and Systematic Affinities

Both records are embedded in the broader taxonomic work on Bornean and Malayan flora that characterised the journal in the first two decades of the twentieth century. Burkill’s description of Plethiandra sahebii is explicitly situated within the history of the genus, which was created by Sir Joseph Hooker in 1867 for a plant collected by Motley on “Gunong Say” in Sarawak [1, p. 265]. Hooker placed it in the Astronieae following Kibessia, and the genus remained of one little-known species, described upon “a rather poor specimen,” until Stapf expanded it considerably [1, p. 265]. By 1896, Stapf had raised the number of species to seven—six from Borneo and one from Singapore—by reducing Cogniaux’s Medinilopsis into Plethiandra and adding new species from Haviland’s Bornean collections [1, p. 265]. Burkill’s addition of P. sahebii as an eighth species was accompanied by a comparative analysis of floral dimensions across the genus, a table showing calyx, petal, and stamen measurements for all known species [1, p. 268]. He argued that the ovary is consistently six-locular across the genus, contradicting Hooker’s count of four for P. motleyi and Cogniaux’s count of three for Medinilopsis [1, p. 268]. The number of stamens is variable, ranging from 20 in P. sessiliflora to about 30 in P. cuneata, with 28 being almost constant in P. sahebii [1, pp. 268–269]. Stapf transferred Plethiandra to the neighbourhood of Medinilla, and Burkill notes that the Philippine genus Carionia, always placed close to Medinilla, is also closely allied to Plethiandra, though its flowers are much larger and its stamens do not exceed twelve [1, p. 269].

Ridley’s note on Lasianthus barbellatus is far less systematic in character. It provides a concise Latin diagnosis and a single plate, without comparative discussion of the genus or its affinities [2, p. 187]. This reflects the different purposes of the two contributions: Burkill’s article is a full species description with taxonomic commentary, while Ridley’s is a brief announcement of a new species, typical of the rapid descriptive work that kept pace with the influx of collections from the region.

Research and Documentation

The two records illustrate different modes of botanical documentation in the Society’s journal during the same volume (No. 77, 1917). Burkill’s article on Plethiandra sahebii is a standard early-twentieth-century taxonomic monograph of a single new species, contributing to the ongoing revision of Bornean Melastomataceae initiated by Hooker, Cogniaux, and Stapf [1, pp. 265–269]. Its central contribution is a morphologically detailed account of the species, uniquely illustrated from life rather than dried material, alongside a comparative analysis of floral dimensions and a brief systematic discussion of its affinities to Medinilla and Carionia [1, p. 265]. The description is based entirely on a single living specimen in the Singapore Botanic Gardens collection, with no herbarium material cited; the plant “has no horticultural value” and was grown solely for determination [1, p. 266]. The archival record thus represents a case in which a shrub of modest size and no economic or horticultural significance was described in full taxonomic detail because of its systematic interest within the genus.

Ridley’s note on Lasianthus barbellatus, by contrast, is a brief taxonomic announcement of a new species collected from Pulau Tiuman, Pahang [2, p. 187]. It provides a concise Latin diagnosis and a single reduced-scale plate, without the comparative or systematic elaboration found in Burkill’s article [2, p. 187]. The two records together demonstrate the range of documentary approaches to shrub species in the journal: from the detailed, illustrated, and systematically contextualised monograph to the rapid, diagnostic species note. Neither record addresses the ecological role, economic significance, or broader distribution of shrubs as a growth form; the subject is treated strictly as a taxonomic category, with the descriptor “shrub” serving to convey habit rather than to initiate ecological or economic discussion.

MBRAS Sources

References

  1. I.H. Burkill (1917). Plethiandra sahebii, a new Melastomacea from Sarawak, described JSBRAS 77: 265–269. Read on JSTOR
  2. H.N. Ridley (1917). Lasianthus barbellatus, a new species from Pulau Tiuman, Pahang JSBRAS 77: 187. Read on JSTOR