Rediscovering Portulaca terrae-reginae Poelln.

While browsing through a CD of photos sent to me by Attila Kapitany, I came across several photos of Portulaca plants that Attila had placed in a separate folder named "Portulaca unknown". Attila tells me that he photographed the plants in Litchfield National Park in the Northern Territory. The photos are date stamped 25th February 2003. 

The plants in the images were interesting from a botanical point of view. They looked rather like depauperate specimens of the common Portulaca oleracea, and it was to this species that I casually dismissed them on first glance. However, the photos began to intrigue me over the course of the next few months.

One day while browsing Urs Eglli's book, Illustrated Handbook of Succulent Plants: Dicotyledons, I came across an entry for a poorly known taxon, Portulaca terrae-reginae Poelln.. The fact that the plant had been collected from Australia and described by von Poellnitz caught my eye. I could not find the description online so asked about its availability at the Queensland Herbarium. Dr Paul Forster kindly sent me a scanned copy. Much to my chagrin I later chanced upon the online version that had previously eluded me! 

The description begins with a brief summary in Latin (which, incidentally, is the same as the entry in Eggli). This is followed by a more detailed German description. 

I soon realized that the taxon described by von Poellnitz was similar, if not identical, to the plants in Attila's photos. The only difference is that the leaves on the plants in Attila's photos are slightly narrower than the latter and perhaps a little more oblong. However the sparse, mostly opposite leaves and the manner of branching are generally the same as that described by von Poellnitz. The leaf shape still fits within the broad limits of the description.

In herbaria there exists only a single sheet of specimens and a duplicate sheet of Portulaca terrae-reginae Poelln. The type sheet comprises five complete specimens, a branch, and a couple dozen fragments. The duplicate sheet comprises a photographic reproduction of the Type sheet and several pressed plant fragments. The type sheet resides in the herbarium collection of  the Swedish Museum of Natural History (S). The duplicate resides in the herbarium of the Botanical Museum Berlin-Dahlem (B).

The botanist Dr. Karl von Poellnitz had described the taxon from specimens collected by "C. Fristedt" in Cardwell on 18 July, 1889. The detailed description of the taxon was published as a spec. nova. by von Poellnitz in 1940, even though the pressed specimens were lacking flowers and he never saw the live plants. His description concludes with the implication that this species may be most closely allied to P. intraterranea J.M. Black. It is possible that the similar epithet “terrae-reginae” was intended to allude to this connection.

As an interesting side note, the "C. Fristedt" who collected the specimen was the Swedish naturalist explorer Conrad Fristedt (1860-1940), who, in the following year, ventured much further north to study the Aboriginal people on Cape York.

I had originally dismissed the plants in Attila's photos as just depauperate specimens of P. oleracea, and indeed Urs Eggli in Illustrated Handbook of Succulent Plants: Dicotyledon (2001) states that P. terrae-reginae is "probably only a form of P. oleracea". However, the plants do differ quite markedly in their morphology.

The plants in Attila's photos can be described as small (around 10-15 cm high at most), tardy, with a noticeably arching growth habit; long, slender, slightly thickened taproot; one or two lower branches that are shorter than the stem yet significantly longer than the upper branches; leaves sparse and small, ovate-cuneate to narrow-elliptic, mostly opposite; stems red; flowers small, presumably yellow or dark yellow(?); capsules dehiscing below middle; seed not seen.

Attila's photos from Litchfield NP are as follows:

Attila Kapitany's photos of a Portulaca sp. that he photographed
in Litchfield National Park in tropical Queensland. The plants
resemble P. oleracea but are generally smaller and more upright
and have sparse, opposite leaves on short lateral branches.

The specimen sheet from which von Poellnitz described the species can be viewed online at: 

http://andor.nrm.se/kryptos/fbo/kryptobase/large/S07-012001/S07-12445.jpg

[Source: Swedish Museum of Natural History website.]

The duplicate sheet can be viewed online (although I sometimes find this website can be a bit "sticky"!):

http://ww2.bgbm.org/herbarium/view_large.cfm?idThumb=286677&SpecimenPK=88624&Loan=1&Flash=True&SpecimenSequenz=1

[Source: Röpert, D. (Ed.) 2000- (continuously updated): Digital specimen images at the Herbarium Berolinense. - Published on the Internet: http://ww2.bgbm.org/herbarium/ (Barcode: B 10 0295254 / ImageId: 286677).]

The description by von Poellnitz was published in "Zwei neue Portulaca-Arten". In Repertorium novarum specierum regni vegetabilis (RSN) 48(4-11): 117-118, 20 May 1940. It appears online, but was published only in Latin and German, and the Latin description is too short to be useful.

http://bibdigital.rjb.csic.es/Imagenes/P0056_48/P0056_48_127.pdf

http://bibdigital.rjb.csic.es/Imagenes/P0056_48/P0056_48_128.pdf

I wish to thank Hellmut Toelken and Neville Scarlett for their kind help with the following translation:

Portulaca terrae-reginae Poelln. 1940

Annual, with long, very narrow turnip-shaped main root, provided with short secondary (lateral) roots. Stems erect or spreading, to 15 cm long, branched; lower branches spreading up to 8 cm long; lower internodes to 5 cm long, upper shorter. Leaves not numerous, opposite or nearly so, rarely a little alternate, obovate or almost an inverted egg shape (i.e. ovate-cuneate), broadly rounded above or rarely almost truncated, without a point, at the base with a 1 mm to almost 2 mm long petiole, flat, dried very thin, thus certainly not very fleshy, glabrous, 1 1/2 — 2 cm long, half to three-quarters as wide as long. Axillary hair inconspicuous (to a) few, barely up to 1 mm long, white, dried not or hardly curly. Flowers few together, terminal, surrounded by some false involucral leaves, which are very similar to the foliage leaves, but usually smaller, and membranous, ovate, long and somewhat abruptly pointed, 3 - 4 mm long bracts, with approximately 5 mm long, broadly ovate, acute or acuminate involucral leaves, otherwise unknown. Below the terminal inflorescence there are two lateral inflorescences similar to the former and often or perhaps mostly on 1 - 1 1/2 cm long, two lateral side branches, their branches somewhat thickened upward, located on the main branch directly under the main inflorescence or slightly below, arranged opposite or alternate. Capsule yellowish or brownish, thin-walled, covered by the withered corolla, ovoid-conical, the lower part 1 1/2 to about 2 mm long, the top not much broadened and here 2 1/2 - 3 mm wide; the lid 3 mm long, obovoid-conical, surmounted by the style base. Seeds several, to more than three, about spherical (roundish), laterally slightly compressed, black, very glossy, 3/4 mm in diameter, with mostly elongated, uneven, forming-towards-the-margins, very-often-slightly-projecting, star cells.

Australia: Cardwell in Queensland, in July 1889, C. Fristedt without No.!, Type in Bot. Museum Stockholm —

 Our species must be compared because of their large, broad leaves with the insufficiently described P. dubia Tepper and with P. intraterranea J. M. Black. - P. dubia has differently shaped leaves, which certainly are comparatively narrower, and numerous axillary hairs; P. intraterranea has only rarely opposite leaves, which are also morphologically different and are comparatively narrower, and the seeds having a different surface sculpturing. - P. digyna F. Muell. ruled out because of significantly smaller, morphologically different leaves, a capsule not covered by the withered corolla, and because of their few, slightly larger seeds, which have a different surface sculpturing, for purposes of comparison. - P. oleracea L. cannot be used to compare, since it all too often has alternate leaves and a capsule which opens in the middle. 

We can presume that von Poellnitz would have been very familiar with Portulaca oleracea, given his years spent in agronomy on a rural estate, and the fact that the species is a common agricultural weed in Europe. He seemed convinced that Fristedt’s specimens represented a unique species and he even states categorically that P. oleracea “cannot be used to compare”. He suggests that his species may be more closely allied to P. intraterranea J.M. Black. It is likely that he chose the similar epithet “terrae-reginae” in order to allude to this connection. He points to the slender, turnip-like taproot, sparsely leafy, upright stems, much shorter branches, and mostly opposite leaves; as well as the capsules which dehisce below mid-way. He was perhaps being a little too prescriptive, given that he never saw the full range of material that occurs in Australia, so P. terrae-reginae may be more suitably ranked as a “microspecies” within what is now known to be a large, very widespread, and highly variable species complex.

Fristedt’s specimens of P. terrae-reginae from Cardwell are intriguing and do warrant further study by modern botanists. The type specimens appear to show tiny granules of sand still clinging on the roots, which suggests the material had been collected from a sandy environment. The town of Cardwell is situated immediately adjacent to the beach and the surrounding countryside is also very sandy. The specimens may simply represent a localized population of salinity-affected individuals, but it is difficult to know for sure as the precise habitat details were never recorded. Additional field work in the Cardwell area may help to answer these questions.

If plants matching the type specimen can be rediscovered at the type location, they may also help to shed some light on other enigmatic yet unresolved taxons in Queensland, such as Portulaca sp. "Blackall" (G.Le Gros AQ101965) and others in the "Q1" folder at BRI.