Case Studies

Trianthema humillima

Trianthema is a genus of flowering plants – but the species Trianthema humillima was described as a moss!

That species name was created by Ferdinand von Mueller and published in 1876. He based his description of the new species on a specimen collected in inland New South Wales, between the Lachlan and Darling Rivers, by a person named Burkitt.

A Census of New South Wales Plants , published in 1916 and compiled by JH Maiden and E Betche , includes the species but with the comment that it "is a doubtful plant". The species was not listed in an earlier census of the plants of New South Wales, published by C Moore in 1884, nor in the 1893 Handbook of the Flora of New South Wales, by C Moore and E Betche.

Much later the following description of Trianthema humillima appears on page 342 (in Part II) of the second edition of JM Black's Flora of South Australia, published in 1948:

One of the smallest of flowering plants, glabrous, the stems only 1-3 mm. long. bearing 2 or 3 fleshy leaves and usually 2-3 almost terminal flowers; perianth 2 mm. long, divided to the base into 5 unequal hyaline acuminate segments; style 1; capsule obovoid, 1 ½ mm. long, opening by a small convex lid; placenta attached to a central column; seeds minute, 60-80 in the lower part of the receptacle.

Near Maitland, Y.P. The type of this moss-like plant came from between the Lachlan and Darling Rivers, New South Wales. The Maitland specimens are in fruit, and it is impossible to discover the number or positions of the stamens. The type-specimens appear to have been in the same condition. Until these and other points are settled, the generic position of the plant must remain somewhat uncertain.

The letters Y.P. stand for Yorke Peninsula and in that second edition Black simply repeats what he had said in the first edition, published in 1924. On page 531 of the second edition's Part III, published in 1952, there is the following correction:

Delete Trianthema humillima F. v. M. Mr. J.H. Willis of the Melbourne Herbarium, informs me that further investigation of the specimens from Maitland, Yorke Peninsula, prove that this is not a flowering plant, but a small moss, Gigaspermum repens (Hook.), Lindb. Mueller mistook the columella of the spore case (sporocarp, sporangium) for the erect free-central placenta of Trianthema and the numerous spores for seeds.

In this correction there is no mention of any examination of the original specimen (i.e the type specimen) on which von Mueller had based his description of Trianthema humillima.

Volume 4 of the Flora of Australia, produced by the Bureau of Flora and Fauna in Canberra and published in 1984 by the Australian Government Publishing Service, contains an account of the species of Trianthema found in Australia. The author of that account, Ann Prescott, wrote that von Mueller's species Trianthema humillima was really a moss but noted that she had not seen the type specimen of that species.

It is most likely that the type specimen was once housed in the herbarium at the Royal Botanic Gardens in Melbourne, since that was von Mueller's institution. In February 2007 Niels Klazenga, a bryologist at that herbarium, confirmed that the specimen could not be found and it is likely that it had already gone missing by the 1950s. J.H. Willis worked at the same herbarium and would undoubtedly have searched for the type specimen of Trianthema humillima when he was investigating the South Australian specimens of that species. Therefore it may be that nobody other than von Mueller has ever studied the type specimen.

There is also the intriguing question as to who identified the specimens from Maitland as Trianthema humillima.

The original description

Here, for curiosity's sake (and for those who wish to test their Latin), is von Mueller's original published description of the species:

Pumila, glabra, foliis minutissimis imbricatis ovatis vel spatulatis saepe acuminatis, floribus in caule brevissimo 1-3, calycis segmentis tenerrime membraneis hyalino pellucentibus setulaceo-acuminatis, capsula minuta globosa polysperma uniloculata membranea, operculo patellari, seminibus minutissimis.
Inter fluvios Lachlan's et Darling's River; Burkitt.
Tota plantula tantum 1½-3''' alta, massulas depressissimas in humo formans. Folia perminuta, sensim in bracteas transientia. Bracteae sepalis fere conformes, sed minores. Sepala 1-1½''' longa, pallida, fructum conspicue superantia. Genitalia ignota. Capsula vix lineam metiens. Semina renato-globosa, nigro-fusca.
Plantula inter Australianas dicotyledoneas quam maxime exigua, locum inter Trianthemas certum nondum tenens, melius forsan in genus proprium (Pomatotheca) post staminum stylorumque repertionem futuram et propter sepala perfecte soluta est demovenda.

It appeared on page 72 of volume 10 of von Mueller's Fragmentorum Phytographiae Australiae.