China 2014

Pam travelled to Yunnan, China in the spring of 2014 to hunt for Primulas. Click image for more...

Primula Rediscovered

Primula bracteata and Primula bullata are found in their type locations after 125 years.

Near Lhasa, Tibet

How do you tell the difference between P. tibetica and P. fasciculata?

Primula ambita in the Wild

The first ever cultivated plant caused a stir at Chelsea earlier this year.

New Primula Book

The latest Primula book is a revision of the 106 species of Primula found in India.

Recent New Primula Species

Primula hydrocotylifolia.
The New Year is a good time to reflect on what is new in Primula. In my Original Description Project, the list of all Primula species is a moving target. In particular, there have been several new Chinese species discovered and described recently but new species aren't limited to China. New species include:

Primula anthemifolia G.Hao, C.M.Hu &  Y.Xu - This tiny species has leaves which resemble those of the Genus Anthemis (pinnately dissected) and was found in Sichuan. It is a member of section Aleuritia, subsection Glabra.

Primula dejuniana G.Hao, C.M.Hu & Y.Xu - Discovered in Sichuan, this species is a member of section Petiolares, subsection Davidii and resembles P. davidii and P. tenuituba but is distinguished by the leaves.

Primula hunanensis G.Hao, C.M.Hu & X.L.Yu - This species is named for the province of Hunan where it was discovered. It is a member of section Carolinella which is noted for its calyptrate (opening by a lid) capsules and is similar to Primula levicalyx.

Primula hydrocotylifolia G.Hao, C.M.Hu & Y.Xu - Discovered in Sichuan and very similar to Primula veitchiana but is smaller and less floriferous. See above and the Species Gallery for more images.

Primula pelargoniifolia G.Hao, C.M.Hu & Z.Y.Liu - A yellow flowered species discovered in Chongqing and most similar to members of section Cortusoides. Named for the "Geranium" like leaves (Pelargonium).

Primula subpyrenaica Aymerich, L.Sáez & López-Alvarado - Discovered in the Pyrenean range in the NE Iberian Peninsula, this species is in section Auricula and is closely related to Primula auricula.

Primula wawushanica G.Hao, C.M.Hu & Y.Xu - The paper for this is accepted but not yet published at this time. It was discovered in Sichuan and is a member of section Petiolares, subsection Davidii.

There are also changes to the taxonomy of Primula. They include:

Primula bullata Franch. var. bracteata (Franch.) P.Eveleigh, J.Nielsen & D.W.H.Rankin
Primula bullata Franch. var. forrestii (Balf.f.) P.Eveleigh, J.Nielsen & D.W.H.Rankin

From the book "The Genus Primula L. in India":
Primula bella Franch. var. moschophora (Balf.f. & Forrest) S.K.Basak & Mati
Primula calderiana Balf.f & R.E.Cooper var. strumosa (Balf.f. & R.E.Cooper) S.K.Basak, Maiti & Hajra
Primula firmipes Balf.f. & Forrest subsp. subansirica (G.D.Pal) S.K.Basak & Maiti
Primula tanneri King var. nepalensis (A.J.Richards) S.K.Basak & Maiti
Primula tanneri King var. peralata (W.W.Sm. & Fletcher) S.K.Basak & Maiti

Happy New Year and Best Wishes to All in 2016!

The Truth about the Blue Nivalids (P. melanops)

Habitat of Primula melanops.
Primula melanops is a name which many people know from cultivated plants, but what is the true species? It was first collected by Handel-Mazzetti in Muli, north of Yanyuan, in 1914, but he didn't describe the plant until 1924 using the name P. leucochnoa. By then, Kingdon Ward had also collected the same species (in 1921) from Muli, very close to the same place and it was then described by Smith and Ward in 1923 as P. melanops, and so that name has priority. There is no doubt they are the same species. In 2009, I saw plants which are this species, but unfortunately the flowers had already gone over. What I would have expected to see are flowers of "deep Tyrian purple, black in the centre" as stated in the original description.

Pam photographing Primula melanops in Muli
Richards includes P. melanops in is his broad definition of P. chionantha, a variable complex of plants, stating that the character used to distinguish between P. melanops and P. chionantha is primarily the color of the farina, and is of no consequence. The original description of P. melanops compared it with P. sinopurpurea but the differences were that it was smaller, white farinose on the leaves, flowers deep purple with a black eye and a long capsule to 2.5cm. The plant in flower is 10-15cm and 35cm in fruit.
Primula melanops in Muli
I don’t have pictures of true P. melanops in flower either in the wild or grown from seed collections from Muli. Because Richards lists it as part of P. chionantha, plants from many different locations have been identified as this species. For example, plants from the Beima Shan in NW Yunnan have been identified as P. melanops but other species that are part of the Blue Nivalids have type locations in this area, so it is more likely that the plants belong to a related species, not P. melanops. I have listed Primula melanops separately in the Species Gallery, where you can find links to the herbarium sheets, but Richards’ point may be valid.

This post is one in a series about Chinese blue nivalids. See the introduction post.

The Truth about the Blue Nivalids (P. farreriana)

Primula farreriana was collected by Farrer and Purdom in the “Ta-Tung Alps, Kansu” in June and July, 1915 (F. 560, Primula No. 29). Ta-tung is a small mountain range east of Qinghai Lake, Qinghai and could be considered a southern extension of the Quilian (Qilian) mountains. Farrer is well know for his descriptive prose, and there are several writings about the 1915 expedition and the Primula itself. His book “The Rainbow Bridge” is a full account of this expedition which started in Sining (Xining, Qinghai) and explored north and slightly east from there. For a few months, Farrer and Purdom made "Wolvesden house" their base and they explored as far to the east as Tien-tang (Tiantangcun) and as far north as Gan Chang Ssu (Ganchankou). Though there is a map in this book, in his “Report of Work in 1915 in Kansu and Tibet” in the Journal of the Royal Horticultural Society vol XLII, there is a crude map, but with better detailed locations.

Farrer's full description of his discovery of Primula farreriana is worth reading, but who could not covet a plant with flowers "And they are of a loveliness singular and phantasmal in their family, very large and ample and round-faced, of a faint blue lavender so subtle as to be almost a French grey, gradually suffused with a white radiation from the misty bull's-eye of intense black-purple at their throat, which continues down the tube inside and out"? In Farrer's famous book "The English Rock-Garden" there is a black and white photograph taken by Purdom of Primula farreriana in the wild.

Primula farreriana was described by Balfour in 1916 and there are type specimens at the British Museum, Kew, two at Royal Botanic Garden (here and here) and the Smithsonian. Farrer's field note, tells us that this species likes shady crevices (in small soil pockets) on either limestone or granite and that it can form large colonies. This species is more robust that other nivalids with thick stocks of sheathing petioles and bud scales, the leaves are elliptic or oblong-elliptic with an obtuse or subacute apex and with an obtusely denticulate margin. The underside of the leaves is covered in thick white farina, as is the apex of the scape and the pedicels. The flowers are pale lavender-blue, prominently annulate and with a dark purple eye and tube. The bracts are linear with a broad base and the calyx is tubular campanulate and tinged with purple.

It is distinct from other similar species by the corolla lobes which are emarginate (notched), the widely winged petioles, the prominent annulus, long bracts and dark colored calyx. Primula woodwardii grows in the same range and has entire corolla lobes and is more pink in color. Apparently P. farreriana has not been in cultivation. If you have a picture of this species, please contact the webmaster.

This post is one in a series about Chinese blue nivalids. See the introduction post.

The Truth about the Blue Nivalids (introduction)

I guess the first truth is that they really aren't blue, but they are certainly species which have purple flowers on the blue tone, rather than the red tone.
Secondly, the Nivalids are what we call members of the Crystallophlomis Section which use to be called the Nivales Section by Pax. These are all sturdy species which overwinter as large resting buds, have spear shaped, fleshy and usually farinose leaves often extending into a sheath like stalk.
The most enigmatic of the blue nivalids are the Chinese species: P. farreriana, P. hoi, P. ionantha, P. lancifolia, P. leucochnoa, P. limbata, P. longipetiolata, P. melanops, P. optata, P. russeola, P. sinonivalis, P. woonyoungiana, P. youngeriana. There are other blue nivalid species, like P. macrophylla, but they belong in a separate discussion.

Below is a table comparing views of Halda, Richards and the Flora of China regarding these names. All agree on P. farreriana, P. woonyoungeriana, youngeriana and P. hoi*. Primula russeola is also consistent with the exception of Halda also listing P. nivalis var melanantha as a synonym. This is definitely incorrect as this is a synonym of P. melanantha, the famous black primula which is now well known from the Zheduo Pass, Sichuan.
Where they differ significantly is in P. limbata, P. longipetiolata, P. optata, P. melanops and P. leucochnoa. Halda confusingly has P. limbata and P. longipetiolata as both distinct and as synonyms.
Flora of China
     nivalis var melanantha
synonym of chionantha subsp melanops
synonym of chionantha subsp melanops
synonym of melanops
     nivalis var melanatha
synonym of P. limbata
synonym of P. optata
     limbata smith
*P. hoi (formerly "hoii", but the spelling has been corrected according to the IAPT code of nomenclature).

In order to understand these species I am researching the original descriptions, type locations, type herbarium specimens and expedition routes of the original collectors to try and understand the similarities and differences between these species. I take nothing for granted, and even though there is agreement between authorities, it is prudent to review all of these species in light of today's information.

This is the first post in a series, with subsequent posts describing these species. I will update this post as I write each new post in the series, so there will always be links to the other posts at the bottom of this one.

1. Primula farreriana post is here.
2. Primula melanops post is here.
3. Primula longipetiolata post is here.

The Chinese Virtual Herbarium (CVH)

A plant species is usually described from a type specimen which is stored in a herbarium. In trying to understand the Genus Primula, I look at Primula herbarium specimens which have been scanned and are available online on websites of herbariums around the world. Relevant websites can be found on my reference page. Sometimes a portal website is created that allows searching through specimens found at several herbariums. The Chinese Virtual Herbarium is a portal into many Chinese herbariums including PE (Institute of Botany, Chinese Academy of Sciences, Beijing), CDBI (Chengdu Institute of Biology, Chengdu), HITBC (Xishuangbanna Tropical Botanical Garden, Academia Sinica, Xishuangbanna), and LBG (Lushan Botanical Garden, Lushan). The herbarium codes can be determined through the Index Herbariorum website.
Logos for the herbariums accessible through the CVH
Ok, so you can't read Chinese! Don't panic, as Google Translate does a pretty good job of translating the Chinese to English (or another language). Just type in the URL in the left box, select Chinese for the language, select English on the right box and click the Translate button. You will see that the CVH search box is capable of using the Scientific name, Chinese name, Collection Number, Collection Location, or the Herbarium Barcode Number. Unfortunately, you can't then use the translated website to enter your data in, just the Chinese version.

Search by Species Name
The easiest search is by leaving the first search type selected (indicated by the black dot) which is search by Species Name, enter the species name and click the green search button. This gives you a list of specimens found at various herbariums for that species. It includes specimens which have scanned images, indicated by a camera symbol. Above is an example using Primula falcifolia. Three of the herbarium sheets are scanned and by clicking on the Herbarium Barcode in the first column a new tab will open with information about the specimen and an image of the sheet. At the bottom of the image is "大图下载 " which is a link to the largest sized version of the image (though often this isn't much bigger). Generally, the scans aren't of high quality, but that should improve over time. Copy and paste the URL for the sheet into Google Translate to get a rough indication of the details for the specimen. Often the translation for locations is too literal, and some sleuthing is required to figure them out exactly (see tab information below).

Original description of Primula homogama
The other type of search I use frequently is by Collection Number (third search type selected, indicated by the black dot). This is the number used by the collector and for types, is listed in the original description. Why would I use this when I can just put in the species name? Sometimes the herbarium sheets are stored under incorrect or unverified names which differ. For example, typing in "Primula homogama" using the species name search returns two results at this time, but neither are type collections. Using the number "31478" which is listed in the original description of Primula homogama above, 28 records are found of various Genera, all with the collection number "31478", but also including four Primula sheets, two under the name "Primula incisa" and two under the name "primula nutantiflora". In theory these four sheets are of the same collection and should be identified the same and the identification should all be Primula homogama. Note that the search results can be viewed by the herbarium barcode (default, first tab) or by number of sheets in each herbarium (second tab),  thumbnails of the specimens with images (third tab), or by map with specimen location shown (fourth tab, I am not sure how accurate this is).

Tip: Copy and Paste the Chinese characters for the Chinese name of a species (see the Flora of China website) and use that to search for images.

The Original Description Project

The Genus Primula was described by Carl Linnaeus in 1753
I started writing blog posts for Primula World as a means of keeping track of research I do behind the scenes while identifying Primula images for the Species Gallery. I consult many references in the process which includes Floras, monographs and related plant books. However these are all interpreted sources: that is, the author is writing about their views of a species. This is valuable in that the author may have seen numerous examples of the species in question, and can then better judge its variations, but for me going back to original sources is a key part of the process. This includes the type herbarium sheets, the original species description and any original documents from the initial collector such as field notes or diaries. It is also necessary to look at species which are considered synonyms: that is, species which were initially considered distinct, but now are considered a part of the variation of a previously described species. My goal is to have a copy of the original description of every Primula species ever described, including subspecies and varieties.

Since species have been described since the mid 1700's, how is it possible to find all the articles containing the original descriptions?

First I started with a list of the species names, including synonyms, from all references available to me. That includes websites such as Tropicos and The International Plant Names Index and books such as monographs or Floras. In some cases the reference website will provide a link to the actual description when it is available. Mainly this is to the reference website, the Biodiversity Heritage Library. The author citation in conjunction with the name is very important as a species name my have been used more than once by two different authorities for very different species. Unfortunately the list I have is not complete as no reference seems provide a definitive list. Often I find names of species from old herbarium sheets, which, thankfully, provide an authority or reference that helps me find the original description. Other times, when I find an original description, I read the rest of the article and find other original descriptions missing from my list (often subspecies or variations).
Beautiful drawings may be included with the original description.
This one from Tableau encyclopedique et methodique des trois règnes de la nature: Botanique

How far have I got on this project?

The IPNI lists over 1800 references for Primula names and Tropicos lists over 1200. So far I have descriptions for about 1400 names. Most of those are available online and when they are, I link to the original description for a species and all of its synonyms in the Species Gallery. If the reference isn't online, there is no link, but I may have a scanned copy of the description from books I have borrowed or from friends that have access to the reference I need. Obscure journals or recent papers still under copyright remain the most difficult for me to find, but slowly I have been tracking them down.

Primula dueckelmannii from the Wakhan Corridor

Primula dueckelmannii is a mystery species, described in 1959 and one that is known to be closely similar to Primula kaufmanniana from Turkestan. The description does not seem to match the herbarium specimen but apparently the difference between the two species is that P. dueckelmannii has seven lobed leaves, deep reddish-violet flowers, hairs on the scape, pedicels, bracts and calyx and the calyx lobes are linear. There are herbarium specimens online at Universität Wien, Vienna : holotype specimen W 1964-0005577 and non-type KUFS 022196.
Primula kaufmanniana
Unfortunately I have no images of Primula dueckelmannii and careful study of it is difficult because it is found in the Wakhan corridor of Afghanistan. This area is considered a challenging place to travel to and possibly dangerous, though it is much safer if you travel from the north via Tajikistan rather than through Afghanistan from the south. 
Wakhan corridor by Hans Roemer
Richards says that expeditions to the Wakhan in the 1960's and 1970's reported seeing P. kaufmanniana which could very well have been P. dueckelmannii. The Wakhan was visited by Hans Roemer in 1964 and his images of P. macrophylla, P. pamirica, aff P. schlagintweitiana and P. warshenewskiana are in the Species Gallery.

Recently Gary and Monika Wescott travelled through the corridor and encountered no problems doing so. There are even upcoming trips planned to the Wakhan for 2016 from Secret Compass, Untamed Borders, Another World Adventures, and Wild Frontiers. If you (or someone you know) are intending a trip to the Wakhan, and you are able to take Primula images for me, please contact me for details of the species to be found there.


The Eye of the Flower - Annulate vs Exannulate

The eyes are the window of the soul.

The eye of a Primula flower is its center which may be colored different from the rest of the corolla and which is the mouth or end of the flower tube containing the stigma or anthers (see Style Position).

In Primula, whether the flower is annulate or exannulate is an important characteristic to differentiate between species.
Close-up of the annulus in a Primula flower
Annulate means having a ring-like constriction (annulus) at the mouth of the flower. A different colored eye from the rest of the corolla does not indicate that an annulus is present. Some species even may be weakly annulate or sometimes exannulate. Exannulate is the opposite; no annulus is present. The best way to determine whether an annulus is present is to slice open the flower.

Slice open a flower to determine annulate (L) vs exannulate (R).
Examples of annulate Primula flowers 
Examples of exannulate Primula flowers

The Lost World of Tibet Film by George Sherriff

George Sherriff (1898-1967) was a famous Scottish explorer and plant collector who travelled primarily with Frank Ludlow in the Eastern Himalayas. Together, they discovered many new plant species including many Primulas. Their expeditions are detailed in the Book "A Quest of Flowers" by H.R. Fletcher. George was an avid photographer and his still images showing plants in the wild are a precious source of information. He also made movies and one of his amateur films from the early 1940's is viewable on You Tube (12mins). It is called "The Lost World of Tibet" and it is narrated by George's wife Betty. It is a fascinating glimpse into travel at the time and there are occasional glimpses of Primulas. See time 4:50 and 6:14.

P. strumosa or P. calderiana subsp. strumosa ?

Primula strumosa
The yellow flowered species, P. strumosa was described from plants found at Champa Pumthang in Bhutan and it was associated with P. elongata  which it distinguished in having a long seed capsule opening by valves. The purple flowered species, P. calderiana, was described from plants found near Changu in Eastern Sikkim. It had been confused with an earlier described species, P. obtusifolia, a nivalid, from which it is easily distinguished by the leaves and seed capsule.

Primula calderiana
P. calderiana and P. strumosa are very similar in their characteristics but differ in flower color, and perhaps scent (this is very subjective) and in their geographical ranges, with P. calderiana distributed in the Eastern part of the Himalayas and P. strumosa distributed to the West. These two species rarely meet, but when they do, hybridization occurs, giving a range of muddy colors.
Primula calderiana X  Primula strumosa
John Richards in Journal of the Scottish Rock Garden Club 15(3):211. 1977. acknowledges that the range of the two species are mostly separate but notes that wild hybrids do occur. His testing of cultivated hybrids shows that they are 100% pollen-fertile. Therefore, he placed P. strumosa as a subspecies of P. calderiana. Often the criteria used to describe a subspecies is if it is capable of interbreeding and producing fertile offspring with the species in the wild, but does not interbreed due to factors such as geographic isolation, etc.

Subsequent to Richards publication, Polunin & Stainton in "Flowers of the Himalaya" (1984) and Gould in Hara, An enumeration of the flowering plants of Nepal" (1982) followed Richards without comment. The Flora of Bhutan (1999) and The Flora of China (1994) retained P. strumosa as a distinct species with comments justifying their positions. Mostly, this is based on notes by Ludlow that in the field, pure P. strumosa was found at a higher elevation than pure P. calderiana and the only hybrids were found at an intermediate elevation between the two pure populations. The recent book The Genus Primula L. in India goes one step further than Richards, in reducing P. strumosa to a variety of P. calderiana but they do not justify this position and do not acknowledge the altitudinal preferences of the two species.

Unless there is more convincing evidence, I am retaining P. strumosa as a distinct species.

Primula Leaf Glossary

There are many terms that are used to describe Primula leaves and an understanding of what they mean is crucial to distinguishing species.

Lamina, or leaf blade, is the flat part of the leaf.
Apex is the point or tip of the lamina.
Base is the bottom of the lamina.
Veins appear as raised lines on the lamina. See Leaf Venation in Primula
Mid rib is the prominent vein which runs from the apex through the center of the lamina.
Margin is the edge of the lamina.
Petiole is the leaf stalk which attaches the leaf to the plant stem.

Each of these parts can vary in shape as shown the diagrams.

Leaf Shapes

Leaf Margins
Leaf Apex, Venation & Bases
Leaves can be petiolate (a petiole is present). Petioles can be distinct (clearly defined), indistinct (not defined) or winged (edged with a thin flange of tissue). It is important when extracting a leaf from a plant for imaging, that the petiole is intact. Remove the leaf by gently tugging downwards along the stem.

Winged petiole

A Primula from the Miocene - P. riosiae

The Miocene is a geological period extending from 23 million to 5.3 million years ago. It is during this time period that the apes arose and humans split to become their own lineage, open grasslands became more prominent and by the end of it almost 95% of modern seed plant families existed.
Evolutionary studies about our own primitive human ancestors makes the news with each exciting discovery, but behind the scenes, the evolution of the Primulaceae is also the focus of ongoing studies. Though genetic studies help us understand the relationships between species, other characteristics, such as seed morphology can be used to help differentiate plant species and to group related species. These days imaging seeds is easily done with clear results. See my Blog post Bringing Seeds into Focus.
Seeds are a goods means of exchanging plant material with like-minded enthusiasts worldwide. Many plant societies offer seed exchanges for their members including the American Primrose Society, Scottish Rock Garden Club, Alpine Garden Society and North American Rock Garden Society which all list Primula in their seed lists. But those are seeds of plants growing today. What would a Primula look like growing in the Miocene?
Primula riosiae from the original description
That is in part what Primula evolutionary studies hope to uncover but we can peek into the past and seed what a Primula seed looked like. The image above is the result of a Paleocarpological study done from samples collected in a lignite mine at Berzdorf, Germany which were dated to the lower and upper Miocene. Three seeds were found and they were then described by Alexander Czaja as a new species called Primula riosiae after Mrs. Anabel Rios in a paper titled "Paläokarpologische Untersuchungen von Taphozönosen des Unter- und Mittelmiozäns aus dem Braunkohlentagebau Berzdorf/Oberlausitz (Sachsen)" published in Palaeontographica Abteilung B Band 265 Lieferung 1-6 (2003), p. 49. The description is brief, but it is noted that the seed shows cells on the surface characteristic of many modern Primula seeds and that the seed bears a resemblance to Primula ruprechtii Kusn., which is considered a synonym of Primula elatior. Two recent papers which have used P. riosiae in their studies are : "Heterostyly accelerates diversification via reduced extinction in primrose" by de Vos et. al. and "Phylogeny and biogeography of Primula sect. Armerina: implications for plant evolution under climate change and the uplift of the Qinghai-Tibet Plateau" by Ren et. al.

Primula rebeccae A.J. Richards a synonym for Primula tenella King

Primula tenella was first discovered in the Chumbi valley, Tibet and was described by King ex Watt in Journal of the Linnean Society. Botany 20:13. 1882  (with a drawing) and also Hooker from Flora of British India 3:492.

Chumbi Valley - Reproduced by permission of Durham University Library and the Bentley Beetham Trust
W.W. Smith in The Genus Primula: Section Minutissimae. Trans. Bot. Soc. Edinb. 33:227-266. (1942),  says P. tenella was first collected in 1878 and again in 1879 in the Chumbi Valley, S. Tibet, by Dungboo, Sir George King’s collector. King recognized it as a new species and on the type (Dungaboo, anno 1878, in Herb. Calc.) has himself written the name giving the locality as Goop, 13 miles from Phari.” The holotype is presumably still at CAL, now Botanical Survey of India, Howrah, but there is no image of the type online.

At the Royal Botanic Garden Edinburgh is an isotype of a single plant with no location information or date, E00024523 and a second sheet collected by Dungboo in 1879 from Seain Chu(?), Chumbi, not available online. In Kew herbarium, there are two sheets online, K000639442, and K000639443. In Paris there is one sheet, P04907201The exact location of Goop is unknown, and access to the Chumbi Valley is restricted, so images from the approximate type location are not available.
Primula rebeccae from the original description
In 2000, Sabine and Georg Miehe found a Primula species growing near Jangothang, Bhutan (27°46'3.01"N 89°20'4.66"E) "at about 4000m and was confined to shady crevices amongst boulders in the vertically river-cut precipice between the flood-plain of the Pa Chu River and the adjoining river terrace. Here it grew in gregarious groups and clumps in a sandy-silt matrix on moss-dominated banks." The Miehe's also found similar plants higher up in the nearby Tso Phu Valley. This species was subsequently described by A.J. Richards as Primula rebeccae in Plantsman n.s., 3(1): 54. 2004. and the holotype is in Edinburgh, E00180782. The type location for P. rebeccae is about 36kms away from the type location for P. tenella.
Type location for Primula rebeccae

Subsequently, in 2008 and 2009, Margaret Thorne travelled to Jangothang and was able to photograph the population in detail showing this species to be highly variable. Notice the flower size, color, petal shape variation in the image above. Also notice how the leaves vary in shape with the exposure, back to front. See also the Species Gallery under P. tenella for more images.
Primula tenella by George Sherriff
In 1944, George Sherriff photographed Primula tenella (#16314) at the Lingshi Glacier, just 10kms away from the P. rebeccae type location. It is obviously the same species as that found by the Miehe's and even though the image is black and white, the pale eye of the flowers is apparent.

Primula caveana

In the original description of P. rebeccae, Richards compared the species to Primula caveana in Section Cordifoliae, a larger species which also grows in the same area. Differences given between the two species were the smaller calyx, filiform (thread like) pedicels, usually solitary flowers, emarginated petals and a pale eye and tube in P. rebeccae. However Richards did not compare the new species with P. tenella in Section Minutissimae, an obvious oversight. It is easy to see that P. rebeccae has the characteristic wedge shaped leaves shown in the original drawing with the original description of P. tenella and that it matches in everyway the (brief) original description of P. tenella.
Below is a map showing some historical collections and the location for P. rebeccae. 
Red- tenella, Blue - rebeccae, Yellow - caveana
(Yellow line is Tibet- Bhutan border)


Primula longipinnatifida

Primula blinii has numerous synonyms reflecting the variability of this species. One of the synonyms cited in the Flora of China is P. longipinnatifida F.H. Chen. This species was collected by T. T. Yü, NW of Wa-Erh-Dje, alt 2800m under woods in 1937. It was described in the article “An Enumeration of Primula Collected by Mr. T.T. Yü From Northwestern Yunnan” by Feng-Hwai Chen in Bull. Fan Mem. Inst. Biol., Bot. 1940. In the original description, Chen compared the specimen to Primula incisa Franchet which is a synonym of P. blinii. P. longipinnatifida was distinguished from P. incisa by having longer pinnatifid leaves, membranaceous in texture and by the smaller corolla tube. Chen cited Yü 6146 in the Herbarium, Yunnan Bot. Inst. (now KUN - Kunming Institute of Botany) but this is an error and the correct collection number is 6046.
Yü 6046 - Photo P. Eveleigh, courtesy Kunming Institute of Botany
Yü 6046 label - Photo P. Eveleigh, courtesy Kunming Institute of Botany

So why discuss this? In 2014 I visited the Kunming herbarium and looked at the holotype specimen of P. longipinnatifida. I was quite surprised that this species was so distinct, especially when compared to the type specimen of P. blinii. The leaves are so dissected they almost defy description. The texture of the leaves is like tissue paper and are not like those of P. blinii, rather they resemble P. runcinata which has leaves that aren’t quite so deeply pinnatifid and which has a different (racemose) flower arrangement.
Yü 6046 inflorescence detail - Photo P. Eveleigh, courtesy Kunming Institute of Botany

Yü 6046 leaf detail - Photo P. Eveleigh, courtesy Kunming Institute of Botany

Wa-Erh-Dje (now Waerzhai) monastery 28°31'53.51"N 100°55'9.06"E was one of three royal residences of the Muli King and was visited by Joseph Rock and illustrated in The National Geographic Magazine in July 1931. Rock described the location of the monastery as “3 days north of Muli”, Muli being the old site of Muli monastery not the present day town named Muli which is 50kms to the SE. Muli county is considered a Tibetan autonomous county within the Province of Sichuan and was an independent kingdom until 1950.  The present day county is split into three districts following the three most important monasteries: Muli, Kulu (Kangwu) and Wachin (Waerzhai). Travel in the northern part of Muli is restricted but foreigners are allowed access to the southern part though it is considered dangerous to travel there with its history of revolts and bandits. Some modern images exist of Waerzhai showing the old monastery ruins and the modern replacement. 

There is no indication by Yü how far to the NW of Wa-Erh-Dje the specimens were collected though the monastery is at 3300m and the collection altitude of 2800m is reached quickly in that direction as you descend to the river valley. Kunming herbarium has other specimens from Muli collected by Yü in the same year filed under P. blinii but unfortunately they are not imaged online so it is impossible to tell at present if they show plants closer to P. longipinnatifida or P. blinii (in the original sense).

This is one of those species that we need more information about and images from the wild showing population variation would go a long way to determining it's relationship with other species. We can only hope that someone will find this species again in the near future.