Thursday, 31 January 2013

Of Fairy Tales and Fairy Bells-part 1

History- The Don of Disporum & Prosartes
Like many a genera these days, Disporum and its sidekick Prosartes, have ‘been around the block’ and felt the sting of the taxonomists boots in the dark alleys of nomenclature. That’ll teach you for hanging out in dark alleys! There was a time when, as nomenclatural debutantes Disporum were feted and the toast of many a treatise. But soon they were ignored, their names were changed and they were left to their own devices. But over the past 15 years with the frequency of exploration in the Sino-Himalayan region yielding many garden-worthy species, it seems that they may have regained their stature and finally found their place. Naturally, the scope of their beauty and the distinctive forms has simultaneously given rise to a better understanding of this genus. But their reputations and the names they’ve been called...oh my!
The genus Disporum was so named by the eccentric R.A. Salisbury in the first volume of the Transactions of the Horticultural Society of London (forerunner of the RHS). The name Disporum that Salisbury coined is a botanical neologism derived from the Greek epistemes “di” (two) and “spora” (seed)- therefore two-seeded. The specific type plant was named pullum and eventually identified as D. cantoniense [Lectotype: Disporum pullum Salisb. = D. cantoniense (Lour.) Merrill.]. However, it was not ‘validly’ published in 1812 due to a lack of a description on Salisbury’s part. James Edward Smith (1818) treated the plant, D. pullum, under Streptopus, and Wallich  later in 1820 nestled it under Uvularia. (To show the sorry state of understanding of the taxonomic truths of Disporum, Graham Stuart Thomas was still using Disporum pullum in his Perennial Garden Plants book in his third edition in 1990!) The honour of actual authorship fell to Scotsman David Don in 1825 as he coordinated and organized the collections of Nathaniel Wallich and William Buchanan cum Hamilton in the seminal Prodromus Florae Nepalensis (aka Flora Nepalensis). It was then that he saw Smith’s and Wallich’s errors.
His involvement in this important publication came about due to the fact that he was the librarian to Aylmer Lambert. Lambert, in turn, had many of the duplicates of plants sent from India and the Himalayas by the energetic Dane, Nathaniel Wallich and, to a much lesser degree, those of William Buchanan cum Hamilton. They were both employed by that great arm of corporate imperialism, the Brtish East India Company. (see Endnotes for much more biographical info on David Don)
In Florae Nepalensis, the characters which David Don concluded were definitive characters to identify Disporum are: 1) campanulate periathium; 2) sepals formed into a pouch or spur at the base; 3) cells of its ovarium bearing two ovula; 4) its baccate pericarpium; and, 5) its umbellate inflorescence. 
14 years later, in 1839, David Don prepared his “Monograph of the Genus Disporum” for the Linnean Society which he read before them. This first Disporum monograph dealt in much greater detail with the specific morphological attributes not only of Disporum but also with related genera namely Uvularia, Streptopus and his proposed authorship of the taxon, Prosartes. In this work, he clearly spells out the errors of Smith, Wallich and others in confusing Disporum, Uvularia and Streptopus which thus gave rise to his proposal of the genus Prosartes.  Here is a little flavour of David Don's observational prowess. 
“In Uvularia, which is closely allied to Disporum, the  perianthium is also campanulate with imbricate aestivation; the stamens adhere to the sepals at the base, and fall off altogether; the pericarpium is capsular with polyspermous cells and loculucidial dehiscence; the ovula which are arranged in two rows are cuneate, angular and carunculate at the apex with the raphe forming an elevated ridge along their inner side.” (p. 514) 
That was truly an amazing description which had me diving into my Penguin Dictionary of Botany! With this statement it is clear that Don was intimately aware of the affinity and differences between Uvularia and Disporum. Molecular biologists Utrecht et al concluded in 1996 that Don was right in the first place to separate them. (reference Endnotes) This latest annoiting of authority took just under 200 years to achieve. In 1841, just before he died, Don provided a detailed addenda to his Disporum et al monograph. 
Don was an astute observer of things microscopically especially the seeds and flower parts. The historian Mark Lawley believes that David Don’s skill of seeing morphological minutae so well was likely due to the fact that he grew up in a vibrant Scottish weaver culture that used hand lenses to examine their weaves. David Don’s father, George Don Sr., was an extraordinary pioneer bryologist and nurseryman that made excellent use of the hand lenses for identifying mosses. (reference Endnotes).  
As for David Don and his insights into Disporum, his message of logical, botanical distinctions subsequently fell on deaf ears or weak eyes. He states that the NE American Prosartes is different from Disporum.  “The genus is essentially distinguished from Disporum by its innate anthers, nearly concrete styles and pendulous anthers.” (p. 44 Proceedings Linnean Soc. 1839). Note that Prosartes gains its name from its pendulous ovula- i.e. from the Greek word, “to append”. 
Robert Wight in his various volumes of Prodromus Florae Peninsulae Indae Orientalis did not see what David Don saw or knew about Disporum. More to the point, he all but ignored Don’s analysis in his publications. Take for example, Wight’s naming of apparently two species of Disporum in Volume 6 of Icon. Pl. Ind. Or. p. 2049. Wight in 1853 authored Disporum ceylandicum and Disporum mysorense as new discoveries when in fact they were both Disporum leschenaultianum. At least the former one from Sri Lanka (Ceylon) was. The latter named one was a mistake by Royle that was duplicated by Wight. Notes the late  modern authority on Disporum, Hara, “ This species does not grow in the Himalayas, and the locality 'Mussooree' cited by Royle (1840) seems to be a mistake, also a plant collected by him is a doubtful one.” (p 24 Tokyo M. Bull. #31,1988) Note that Mussoorie is located in Uttarakhand in North India. Wight by the time he came back from India was burned out and he really didn’t care about the distinctions. Neither did Joseph Hooker.
Joseph Hooker was dimissive of the differences between Disporum and Prosartes, the latter he referred to as “doubtfully distinct” (Curtis Bot. V. 113 Tab 6935). Together with Bentham, the differences that Don had detailed were rejected as valid when they published in 1883 (Gen. Pl. vol. 3, p. 831). In fact, authorship for the genus Disporum was still attributed to Salisbury and they dropped Disporum from consideration calling all species in India, etc. Uvularia! (“Flora of British India” Vol. 6 1894.) Thus, Don was expunged from authorship by some heavy hitters. But the eclipse of Don was only for a while albeit a very long while.
The accepted viewpoint of Hooker, Bentham, etc. came to a halt in 1951 with the publication by Jones in the “Contributions from the Gray Herbarium” (Jones, Q. 1951. “A cytotaxonomic study of the genus Disporum in North America.”) In this publication (vol.173: pp.3 - 40.), Jones concurred with Don that Prosartes was indeed a valid genus with morphological and cytological distinctions worthy of separate taxon status. He also found for the rule of priority under the Botanical Code for Disporum. ( Editorial: Modern authors want merely to credit David Don with the creation of a Section Prosartes. I am no expert in the finer points of the Botanical Code but Don proposed a new taxon not just a new Section. Therefore, should not Don’s name should be on all Prosartes not Smith’s or Hooker’s? Talk about adding insult to injury!)
Resurrecting Hiroshi Hara
About 150 years after David Don’s pioneering work on the genus, the eminent Japanese botanist, Hiroshi Hara, prepared the last great monograph on Disporum. In 1988, this monograph was published posthumously in the Tokyo Museum Bulletin #31. It is unfortunate that this major work is still relatively unknown and little discussed. Is history going to repeat itself in ignoring significant treatments of the Disporum genus? No one has ever been as intimate with the differences and nuances of Disporum species as Hara and nobody since David Don himself has done as much analysis of the Disporum/Prosartes complex as the late Hiroshi Hara. To the best of my knowledge, no modern botanist has ever made such an extensive and global use of Disporum herbaria vouchers and specimens. Recently, Julian Shaw did some important work at Kew on the genus that shows up in The Plantsman of December 2011. But Hara did the heavy, herbarium lifting. In so doing, historical lectotypes were validated or not and, overall,  a thorough analysis and sorting out of the species was realized. 
This was not done however, without Hara doing time-consuming field work conducted over a long period of time.
Here is the list of institutions (in alphabetical order with their codes bold-faced) that enabled Hara to look at all things Disporum: British Museum (Natural History), London (BM) ; Royal Botanic Garden, Edinburgh (E); South China Institute of Botany, Academia Sinica, Kwangchow (IBSC); Royal Botanic Gardens, Kew (K); Kunming Institute of Botany, Academia Sinica, Kunming (KUN); Department of Botany, Faculty of Science, Kyoto University, Kyoto (KYO); Laboratoire de Phanerogamic, Museum National d'Histoire Naturelle, Paris (P); Institute of Botany, Academia Sinica, Peking (PE) ; Faculty of Agriculture, Hokkaido University, Sapporo (SAPT); Department of Biology, Sichuan University, Chengdu (SZ); Department of Botany, National Science Museum, Tokyo (TNS).
As a result of this comprehensive activity and work, Hara realigned sections within Disporum and declared Prosartes to be a valid section if not a different genera. Hara proposed three sections: Section Disporum, Section Ovalia and Section Paradisporum. The Section previously denoted as Prosartes now has its own generic status as proposed by David Don (some 170 years earlier!) and is no longer included within the genus Disporum. Hurray for Don! And, hurray fro Hara.
Here is Hara’s broad sectional strokes. Section Ovalia has one species, Disporum ovalia. Section Paradisporum has one species, Disporum acuminatum. Section Disporum has all of the remaining species. 
Within the Section Disporum, Hara does varietalize extensively as well as acknowledging, naming and using forma (forms). I find this an acceptable approach and one that more and more taxonomists are taking with their ‘Group’ assignments to all of the grexy forms. This both/and method is to be preferred over the either/or. Call it ‘creative lumping’ or ‘anti-splitting’ but it does work better in many ways until there are some definitive taxonomic beachheads established. Note that many of the morphological keys are still used in the identification of many species. No, we haven’t quite yet thrown out the morphological baby with the molecular bathwater, so to speak.
With confusion on the botanical front, is it any wonder that there is twice as much on the horticultural front?  However, I believe that Hara’s treatment serves horticulturists well. Remember that Hara and his colleagues were well-versed in cytological analysis as a key in plant identification. Hara’s Disporum monograph is replete with pollen profiles as well as electron photos of seeds. Still Hara’s detailing of significant morphological differences in the species of Disporum is very handy for plantsman. Not surprisingly, many “authorities” do not fully recognize his categories or species. However, we are recognizing them fully and in this sense then we are resurrecting Hara for serious consideration.
As a final note, botanist Julian Shaw as part of the article written by that fine Welsh plantsman, Bleddyn Wynn-Jones, in the December 2011 issue of The Plantsman follows Hara's approach. All of my research was done before this article was published.

Endnotes:
(Amended and adapted from Mark Lawley to which much credit must go)

David Don was born on 21 December 1799 at “Doo Hillock”, Forgarshire, Scotland, into a family of modest means. His father, George Don Sr. was an amateur pioneer (and later celebrated ) bryologist and an accomplished gardener and nurseryman. Thus, it comes as no surprise that David Don would have developed a great eye for detail from his father. George Don Sr. met famed botanist Robert Brown in 1791 (when the latter was a medical student at Edinburgh) and they botanized the Highlands around Angus together making many new discoveries. The following year Brown read a paper regarding this trip with Don before the Edinburgh Natural History Society. The Brown connection would stand young David Don in good stead. Just before David Don was born, in 1797, George Don leased two acres of land on the north side of Forfar. The plot he named as Doo Hillock (or Dove Hillock) after the land’s small knoll. Don established a nursery  on ground sloping down westwards from the knoll, and stocked it with a variety of hardy plants (mostly alpines!) that exceeded most other nurseries in the kingdom. When his good friend John McKay died in 1802, George Don succeeded him as head gardener of the RBGE, leaving his father to run the nursery at Dove Hillock. Four years later he returned to the nursery wanting the freedom of self-employment.  Things didn’t go well for George Don Sr. in business and in health and he died penniless in 1814. His nursery and tenancy was taken over by a 20 year old Thomas Drummond, soon to make a reputation as a botanist in western and arctic Canada but not before spending the next ten years at Doo Hillock growing plants and raising a family. All specific epithets ending with drummondii are attributable to Thomas Drummond.

And so it was that David Don after working with his older brother, George Jr. at the Dickson Nursery in Broughton near Edinburgh, then followed his elder brother on down to London and the Chelsea Physic garden in 1816.  David Don loved what he was doing and soon became the librarian to Aylmer Lambert. As an autodidact, he devoted his energies to learning the library's content- one of the best collection of botany books in private hands- and then applying that knowledge to the vast collections in Lambert's large herbarium. 
David Don began to publish in 1820 and continued unstopped until his death in 1841. In total, he published over 50 botanical articles, as well as volumes 5–7 of Robert Sweet’s “British Flower Garden” (1831–1837). Later in 1837 he married Mary Evans (1796/7– 1866) in London but they had no children.

In 1822, Don also became librarian to the Linnean Society of London. In 1836 David Don rose to the position of professor of botany at King's College. In this regard he followed a path blazed by John Lindley (son of a nurseryman, a librarian and eventually professor at King’s College) Both men took a deep interest in seed morphology and embryo structure as a key to identifying plants. In this regard, they became close friends with botanist Robert Brown and the preeminent botanical illustrator of his time, Franz Bauer
The microscope was a key tool shared by all of these men and they developed terminology to describe what they saw though it magnifying lens. In this sense then this core group including Lindley, we far ahead of subsequent botanists that laboured in the field.

NB: Photos and more info to follow in Part 2

-Grahame Ware, independent horticultural historian




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