Eriinae

Belongs within: Epidendroideae.

The Eriinae are a group of orchids bearing flowers with a hinged, motile lip and a usually short, massive column with a prominent column foot.

Woolly orchids

Published 24 April 2021

The orchids of the Orchidaceae are widely recognised as one of the most diverse families of plants in the modern world, both in number of species and morphologically. They are readily distinguished from other flowering plants by a unique combination of features including the fusion of the male and female organs of the flower into a central column. Rather than being released as individual grains, pollen is aggregated into compact masses called pollinia that are attached to pollinators as whole units. Most orchid species also have the lower of the flower’s three petals enlarged and differentiated into a distinctive lip that may present a bewildering array of shapes and colours. Because of their striking and colourful appearance, many orchids have long attracted attention from humans and many are popular ornamentals. But there are also some major groups of orchids that have been more neglected and one such group is members of the subtribe Eriinae.

The Eriinae comprise about a thousand known species of orchid found mostly in the tropics of Asia and the west Pacific, with a handful of species described from Africa. Most are epiphytes and lithophytes (growing on rocks); a smaller number are terrestrial. Because the flowers of eriines tend to be fairly small and simple, they have attracted less notice than other members of the family, but in some parts of their range they are among the most abundant epiphytic orchids (Ng et al. 2018). Within the Orchidaceae, eriines are a subgroup of the subfamily Epidendroideae, characterised by compact, laterally compressed pollinia, and the tribe Podochileae, with duplicate leaves, a short and massive column, and often spherical silica cells in the stems (Szlachetko 1995). The features distinguishing Eriinae from other subtribes of Podochileae are more vague and there are reasons to believe the Eriinae ultimately represent the paraphyletic residue of the tribe once the more specialised subgroups are removed (Ng et al. 2018). One recent classification of the orchids recommended abandoning subtribes within the Podochileae altogether (Chase et al. 2015). Nevertheless, features characteristic of most eriines include a terminal or upper lateral inflorescence, eight pollinia per flower, and sticky caudicles on the pollinia composed of apical pollen grains. The lip is commonly divided into three lobes. Another common feature of the group (and the inspiration for the name of the type genus Eria, meaning ‘woolly’) is a covering of hairs on the flower and sometimes the inflorescence. In one genus, Trichotosia, the leaves are also hairy.

Historically, the majority of eriines have been included in a broad genus Eria. However, as with the subtribe as a whole, recent studies have indicated that this sense of Eria is not monophyletic and hence its species should probably be divided between several genera. Ng et al. (2018) recognised 21 genera among the eriines. The African species, previously placed in their own genus Stolzia, were united with the closely related Asian genus Porpax.

The pollination biology of eriines is, for the most part, not well known. Some have speculated that they were pollinated by beetles; one website I found showed pollinia attached to a gnat. The two species of the genus Callostylis have flowers whose appearance suggests pollination by pseudocopulation (tricking male insects into attempting to mate with them by mimicking females) but such flowers are unique within the Podochileae (Ng et al. 2018). At least some eriines have flowers producing ‘pseudopollen’ from broken-off hairs (Pansarin & Maciel 2017). This pseudopollen is collected and eaten by pollinators. Thus, though the most common means of attracting pollinators among orchids is via deception, at least some eriines are willing to pay their way in life.

Systematics of Eriinae

<==Eriinae
    |  i. s.: EpiblastusA86
    |         MediocalcarA86
    |         PorpaxA86
    |         SarcostomaA86
    |         StolziaA86
    |--EriaC03
    |    |--E. albaSS72
    |    |--E. andamanicaDAC05
    |    |--E. annulataP03
    |    |--E. armeniacaT-W89
    |    |--E. bractescensDAC05
    |    |    |--E. b. var. bractescensDAC05
    |    |    `--E. b. var. kurziiDAC05
    |    |--E. cochleataT-W89
    |    |--E. convalarioidesT-W89
    |    |--E. denticulataT-W89
    |    |--E. dillwyniiT-W89
    |    |--E. (sect. Conchidium) extinctoria (Lindley) Oliv. 1871 [=Dendrobium extinctorium Lindley 1836]DAC05
    |    |--E. flavaT-W89
    |    |--E. fusco-virideT-W89
    |    |--E. javanicaC03
    |    |--E. leucostachysT-W89
    |    |--E. mucronataT-W89
    |    |--E. multifloraT-W89
    |    |--E. nutansT-W89
    |    |--E. obesaT-W89
    |    |--E. oblitterataP03
    |    |--E. ovataT-W89
    |    |--E. panneaT-W89
    |    |--E. polyuraT-W89
    |    |--E. retusaP03
    |    |--E. stellataTW89
    |    |--E. velutinaT-W89
    |    |--E. verruculosaP03
    |    `--E. vestitaT-W89
    `--+--BryobiumC03
       |    |--B. pubescensC03
       |    `--B. retusum [incl. Phreatia congesta Rolfe 1890]JG19
       `--Oxystophyllum Blume 1825 (see below for synonymy)C03
            |--*O. rigidum Blume 1825 (see below for synonymy)C03
            |--O. acanthium (Schlechter) Clements 2003 [=Dendrobium acanthium Schlechter 1912]C03
            |--O. ambotiense (Smith) Clements 2003 [=Dendrobium ambotiense Smith 1928]C03
            |--O. araneum (Smith) Clements 2003 [=Dendrobium araneum Smith 1913]C03
            |--O. atropurpureum Blume 1858 [=Dendrobium atropurpureum (Blume) Miquel 1855]C03
            |--O. atrorubens (Ridl.) Clements 2003 [=Dendrobium atrorubens Ridl. 1896]C03
            |--O. bipulvinatum (Smith) Clements 2003 [=Dendrobium bipulvinatum Smith 1913]C03
            |--O. buruense (Smith) Clements 2003 [=Dendrobium excavatum var. buruense Smith 1928]C03
            |--O. capitellatum Clements 2003 [=Dendrobium capitellatum Kraenzlin in Engl. 1910 non Smith 1906]C03
            |--O. carnosum Blume 1825 (see below for synonymy)C03
            |--O. changjiangense (Cheng & Tang) Clements 2003 [=Dendrobium changjiangense Cheng & Tang 1980]C03
            |--O. cultratum (Schlechter) Clements 2003 [=Dendrobium cultratum Schlechter 1911]C03
            |--O. cuneatipetalum (Smith) Clements 2003 [=Dendrobium cuneatipetalum Smith 1927]C03
            |--O. deliense (Schlechter) Clements 2003 [=Dendrobium deliense Schlechter 1912]C03
            |--O. elmeri (Ames) Clements 2003 [=Dendrobium elmeri Ames 1912]C03
            |--O. excavatum Blume 1825 [=Dendrobium excavatum (Blume) Miquel 1855]C03
            |--O. floridanum (Guillaumin) Clements 2003 [=Dendrobium floridanum Guillaumin 1965]C03
            |--O. govidjoae (Schlechter) Clements 2003 [=Dendrobium govidjoae Schlechter 1912]C03
            |--O. hagerupii (Smith) Clements 2003 [=Dendrobium hagerupii Smith 1922]C03
            |--O. helvolum (Smith) Clements 2003 [=Dendrobium helvolum Smith 1912]C03
            |--O. hypodon (Schlechter) Clements 2003 (see below for synonymy)C03
            |--O. kaudernii (Smith) Clements 2003 [=Dendrobium kaudernii Smith 1927]C03
            |--O. lepoense (Schlechter) Clements 2003 [=Dendrobium lepoense Schlechter 1911]C03
            |--O. lockhartioides (Schlechter) Clements 2003 [=Dendrobium lockhartioides Schlechter 1910]C03
            |--O. longipecten (Smith) Clements 2003 [=Dendrobium longipecten Smith 1928]C03
            |--O. minutigibbum (Smith) Clements 2003 [=Dendrobium minutigibbum Smith 1914]C03
            |--O. moluccense (Smith) Clements 2003 [=Dendrobium moluccense Smith 1914]C03
            |--O. nitidiflorum (Smith) Clements 2003 [=Dendrobium nitidiflorum Smith 1913]C03
            |--O. oblongum (Ames & Schweinfurth) Clements 2003 [=Dendrobium oblongum Ames & Schweinfurth 1920]C03
            |--O. oligadenium (Schlechter) Clements 2003 [=Dendrobium oligadenium Schlechter 1910]C03
            |--O. paniferum (Smith) Clements 2003 [=Dendrobium paniferum Smith 1914]C03
            |--O. sinuatum (Lindley) Clements 2003 [=Aporum sinuatum Lindley 1841, Dendrobium sinuatum]C03
            |--O. speculigerum (Schlechter) Clements 2003 [=Dendrobium speculigerum Schlechter 1910]C03
            |--O. subsessile (Schlechter) Clements 2003 [=Dendrobium subsessile Schlechter 1912]C03
            |--O. torricellianum (Kraenzlin) Clements 2003 (see below for synonymy)C03
            |--O. tropidoneuron (Schlechter) Clements 2003 [=Dendrobium tropidoneuron Schlechter 1911]C03
            |--O. tumoriferum (Smith) Clements 2003 [=Dendrobium tumoriferum Smith 1910]C03
            `--O. validipecten (Smith) Clements 2003 [=Dendrobium validipecten Smith 1928]C03

Oxystophyllum Blume 1825 [=Aporum sect. Oxystophyllum (Blume) Brieger 1981, Dendrobium sect. Oxystophyllum (Blume) Miq. 1855]^C03

Oxystophyllum carnosum Blume 1825 [=Dendrobium carnosum (Blume) Reichenb. in Walpers 1861 nec Presl. 1827 nec Teijsm. & Binn. 1853]^C03

Oxystophyllum hypodon (Schlechter) Clements 2003 [=Dendrobium hypodon Schlechter 1910, Aporum hypodon (Schlechter) Rauschert 1983]^C03

*Oxystophyllum rigidum Blume 1825 [=Dendrobium rigidum (Blume) Miquel 1859 nec Brown 1810 nec Lindley 1830, Aporum rigidum (Blume) Brieger 1981]^C03

Oxystophyllum torricellianum (Kraenzlin) Clements 2003 [=Dendrobium torricellianum Kraenzlin in Engl. 1910, Aporum torricellianum (Kraenzlin) Rauschert 1983; incl. D. atrorubens Schlechter in Schumann & Lauterb. 1905 non Ridl. 1896, D. simile Schlechter 1906 non Schlechter 1905]^C03

*Type species of generic name indicated

References

[A86] Atwood, J. T. 1986. The size of the Orchidaceae and the systematic distribution of epiphytic orchids. Selbyana 9: 171–186.

[C03] Clements, M. A. 2003. Molecular phylogenetic systematics in the Dendrobiinae (Orchidaceae), with emphasis on Dendrobium section Pedilonum. Telopea 10 (1): 247–298.

[DAC05] Diwakar, P. G., D. K. Agrawala & H. J. Chowdhery. 2005. Eria extinctoria (Lindl.) Oliv. (Orchidaceae)—a new record for India from Andaman & Nicobar Islands. Bulletin of the Botanical Survey of India 47: 197–200.

[JG19] James, D. J., P. T. Green, W. F. Humphreys & J. C. Z. Woinarski. 2019. Endemic species of Christmas Island, Indian Ocean. Records of the Western Australian Museum 34 (2): 55–114.

Ng, Y. P., A. Schuiteman, H. A. Pedersen, G. Petersen, S. Watthana, O. Seberg, A. M. Pridgeon, P. J. Cribb & M. W. Chase. 2018. Phylogenetics and systematics of Eria and related genera (Orchidaceae: Podochileae). Botanical Journal of the Linnean Society 186: 179–201.

Pansarin, E. R., & A. A. Maciel. 2017. Evolution of pollination systems involving edible trichomes in orchids. AoB Plants 9: plx033.

[P03] Partomihardjo, T. 2003. Colonisation of orchids on the Krakatau Islands. Telopea 10 (1): 299–310.

[SS72] Singh, V., & H. Singh. 1972. A contribution to the flora of Gangolihat block in Pithoragarh District. Journal of the Bombay Natural History Society 69 (2): 352–368.

Szlachetko, D. L. 1995. Systema Orchidalium. Fragmenta Floristica et Geobotanica Supplementum 3: 1–152.

[T-W89] Tenison-Woods, J. E. 1889. On the vegetation of Malaysia. Proceedings of the Linnean Society of New South Wales, series 2, 4 (1): 9–106, pls 1–9.