Leptoceras and Leporella – Why are they in different genera?

QUESTION: Are there more than one species called Hare Orchid? This one [Leporella fimbriata] looks different from Leptoceras…?  Why are they in different genera?

 

ANSWER:

Originally they were described the genus Caladenia but as the knowledge information increased other genera were created.  Thus Leporella fimbriata was put into Eriochilus, as Eriochilus fimbriatus (1882), then Leptoceras fimbriata and finally into its own genus Leporella (A S George 1971).  Caladenia menziesii became Leptoceras menziesii.

This does not answer the why of the question which is about classification but Jones (2006) is helpful when he says:

“Plant classification systems rely on interpreting and measuring the features in one group of plants and comparing these with another group, either seeking difference or similarities.  Studies in orchids are usually biased heavily towards features of floral morphology but recent studies have revealed the importance of vegetative features in the roots, stems and leaves.  The most successful classification system is one that is balanced and based on a wide range of vegetative and floral features.”  To add to this list is the molecular studies being done on orchids.

This means the authors advocating change need to clearly show why a name change and/or a new species is warranted.

For instance, Fitzgerald gives the following reason for not including Leporella fimbriata in the Caladenia genus

“Leaves much more frequently observed than flowers.  It is with great reluctance I depart from the naming in ‘Flora Australiensis’ [author Bentham, 1863 – 1878], but I cannot concur with the inclusion of this with Caladenia, and have place it in Lindleys’ Leptoceras for the following reasons: Leaf or leaves not those of Caladenia.  In Caladenia I have never seen more than one leaf, always thin and usually hairy; in this plant leaf thick, hard and shining, occasionally two.  In Caladenia tubers are generally numerous, in L. fimbriata I have only observed one.  The labellum, is without the characteristic glans and is not of the form obtaining in Caladenia, the stigma is very different in form being triangular and deep sunk, the upper parts overhanging, not oval and shallow; and the flowers have the peculiarity of drying and continuing in a state hardly to be distinguished from the fresh flowers long after the seed has been shed.  It approaches C. menziesii only (so far as I can see) in having erect linear-clavate petals, in which C. menziesii is itself peculiar, L. firmbriata seems to come near to Eriochilus than to Caladenia but differs from it again” Quoted from Emily Pelloe Western Australian Orchids 1930

Concerning Leptoceras menziesii, Bates & Weber have made the following statement:

“True Caladenias have hairy scapes and hairy leaves.  (C. menziesii now believed to belong to a separate genus is glabrous)”.

Even though they are not Caladenia, why not have them in the same genus for both have glabous (without hairs) leaves, more leaves than flowers, erect spathulate (spoon shaped) glandular petals, colony forming, similar distribution.

Leporella fimbriata  in patch

Leporella fimbriata – note the absence of leaves and the dry sandy conditions [Photo: R Lawrence]

Leptoceras menziesii in patch

Leptoceras menziesii – note the abundance of leaves [Photo: R Lawrence]

There are similarities.  In fact, Bates (2011) calls them sister genera but despite the similarities there are enough differences to recognise them at genus level at present including “different flowering times, different mycorrhizal fungi associations and different pollination” some of which are detailed in the chart below.

 

Feature Leptoceras Leporella
Pollination Strategy Strategy unknown

Native Bee

Strategy pseudocopulation

Winged male ants (Myrmecia urens)

Myrmecophyte – lives in mutualistic association with colony of ants
Labellum Curved white with red stripes

Has calli

Wider than longer, purple and green

Has no calli

Flowering Time Spring (September to November) Autumn (March to May)
Habitat Shaded sites – moist gullies; scrub, heath, woodland and foret Open sites – acid sands, light scrub, stringybark
Leaf Emergence Leaves emerge before flowering Leaves emerge after flowering

 

Leptoceras menziesii (Rabbit Ears Orchid)

Leptoceras menziesii (Hare Orchid or Rabbit Ears Orchid) after a fire, [Photo: R Lawrence]

REFERENCES:

https://en.wikipedia.org/wiki/Myrmecophyte accessed May 13 2016

http://www.flora.sa.gov.au/cgi-bin/speciesfacts_display.cgi?form=speciesfacts&name=Leporella_fimbriata accessed May 13 2016

http://www.flora.sa.gov.au/cgi-bin/speciesfacts_display.cgi?form=speciesfacts&name=Caladenia_menziesii accessed May 13 2016

Pelloe E, Western Australian Orchids 1930

Bates R & Weber J, Orchids of South Australia, 1990

Bates R Editor, South Australia’s Native Orchids 2011

Martin A, The Vocabulary of Orchids: an Amateur Perspective 2005

Rogers R, South Australian Orchids 2nd Ed 1911

Jones D, A Complete Guide to Native Orchids of Australia including the Island Territories 2006

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