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.

The Mysterious Primula of Omta Tso (Bhutan)

Omta Tso, Bhutan
In November, 2016, I visited the herbarium at the Royal Botanic Garden Edinburgh to study non-type herbarium sheets which are unavailable online. One of the species I wanted to investigate is Primula tsariensis which was described from a collection made in 1936 by Ludlow & Sherriff in the Tsari valley, SE Tibet  28°41'29.98"N 93°23'57.85"E.

It was initially compared with Primula griffithii and P. tanneri but it was distinguished by leaves which are rounded at the apex, bluntly crenulate at the margin and a calyx which is sparsely farinose and glandular. The flowers are described as rich purple.
Primula tsariensis
Going through the herbarium specimens, I came across a folder labelled "P. tsariensis yellow form". What is that?!! All of the collections of this form were Ludlow & Sherriff's from the area near Omta Tso  27°42'54.88"N 90°17'17.96"E in the upper Richen Chu valley, Bhutan. In 1937, Sherriff explored this place and so I traced his 1937 route using his diary and field notes. Sherriff mixed up the names of the two lakes Omta Tso and Thita Tso, so his initial collection #3383 is from the hillsides and shores of Omta Tso (not Thita Tso as stated in his notes). Sherriff gave it the name "Primula strumosa var. nana floribus maximus". Later, W.W. Smith & Fletcher gave it the name "Primula strumosa var. perlata" and in the Flora of Bhutan it is included by that name as a synonym under P. tsariensis. In the genus Primula, there are a number of species which have both purple and yellow forms, so the idea of a yellow P. tsariensis is acceptable.
Primula species of Omta Tso, Bhutan
Continuing to trace Sherriff's 1937 route, I found that he took a two day side trip (July 13-14) from Omta Tso, westwards along the ridge to Chore (I don't have an exact location for Chore, but it would seem to be a yak herder hut at the base of a cliff SW of Omta Tso) and then followed the main ridge south until descending to Maruthang via a steep gully. Sherriff said "I have never seen so many alpines out together as on this march. In places the hillsides and cliffs were just covered with them and the variety was great."
Omta Tso area, Sherriff 1937 - hybrids found along the orange route
Between Omta Tso and Chore, Sherriff came across a little grassy hollow 50 ft. x 50 ft. where there was a swarm of primulas of at least eight shades of colors including yellow, white, purple and blue. These same colors are seen in hybrids where P. calderiana crosses with P. strumosa. Essentially P. strumosa and P. calderiana are yellow and purple forms of the same species, though they have different geographical areas and P. strumosa grows at higher elevations.
Color variations of P. calderiana X P. strumosa
Sherriff knew these were hybrids but couldn't decide which species were the parents. To further complicate matters, Sherriff also found that the yellow, white and blue-purple flowered plants grew in separate masses of one color only. However, the white masses included a few variations of yellow tinged, or blue tinged plants. Sherriff collected what he said was true P. calderiana (L&S 3437) and that it was distinct from the others and not involved in the hybrids. In the field notes, someone (perhaps W.W. Smith) later wrote in the margin "I believe these are normal hybrids of P. calderiana and P. strumosa" and included a reference to hybrid L&S collections from Weitang and Pangotang (Tsampa), Bhutan in 1949, which are unfortunately I haven't seen.

So are the plants at Omta Tso P. tsariensis or are they P. strumosa?

The most obvious differences between the two species are that P. calderiana / P. strumosa smells "disagreeable", and has farina present on the bud scales, and on the upper scape, calyx and pedicels whereas P. tsariensis is not noted for its smell, has efarinose bud scales and only trace amounts of farina on the pedicels and calyx.
Bud scales - (L) no farina, P. tsarieneis, (R) with farina, P. strumosa
Sherriff was limited in his ability to document these plants but certainly more images can shed light on this problem. If you travel to this area and encounter these plants, please take lots of images of the flower color variations, showing the calyx, the basal bud scales, and leaves. And take a sniff!

Pam Eveleigh © 2017

The Black Mountain (Bhutan) - Primulas and Problems

Jigme Singye Wangchuck National Park covers 1,730 sq kms in south-central Bhutan and contained within the park is Durshingla, the Black Mountain. (JSWNP Facebook page)
Durshingla © Darlo Letro
In 1915, Roland Edgar Cooper made the first botanical expedition to Durshingla, which he called Joedawnchi. From Cooper's 1914 and 1915 Bhutan expeditions, 19 species of Primula were described though only six are now considered to be distinct species: P. chasmophila, P. eburnea, P. erythrocarpa, P. strumosa, P. umbratilis and P. xanthopa. He wrote about those trips and specifically about the Primulas he found in Notes of the Royal Botanic Garden Edinburgh, Vol.18, Nov. 1933.

Ludlow and Sherriff (L&S) visited Bhutan several times and Sherriff's 1937 expedition was specifically to Durshingla which he called Dungshinggang. He found no new Primula species there but he was able to recollect known species.

Sherriff's route up Durshingla in 1937
Both expeditions used a route from Chendebi, travelling west over the Lamse La into the Phobjikha valley. From there they ascended the ridge over the Byasu La to Chapepusa and then followed the ridge east until it met the main N-S ridge leading to the peak.

Primulas & Problems

1. The most interesting species found on Durshingla is Primula chasmophila and, so far, it is only found on this mountain. Cooper first discovered it in September and his herbarium specimen was sparse, so it was described from cultivated plants grown from seed. Sherriff collected it on the mountain ridge near the Nabzi La. Though it was scarcely in flower, he noted its deep, rich blue violet color, red eye and its cliff ledge habitat and compared it with Primula umbratilis, a much more widespread species that is also found on the mountain (Cooper 4822). What to photograph if you see this species? Variations in flower color, details of the hairs on the flower scape, leaf study.
Primula chasmophila L&S 3301,
courtesy Royal Botanic Garden Edinburgh
2. The type of Primula hopeana was collected by Cooper on Durshingla, in September, so the plants were in seed. In the description it was noted that sometimes the tube of the flower was "pink", which was seen by Sherriff on the mountain and is seen in populations in Arunachal Pradesh. This species resembles Primula sikkimensis and is sometimes considered a variety of it. Species in the Sikkimensis Section hybridize in the wild and it is very difficult to sort some populations into species. Sherriff noted that he saw true (yellow) sikkimensis here also, so I would expect some hybridizing. What to photograph if you see this species? Leaf study with the corresponding flower color and flower shape. Variations in flower color (don't forget to also show the flower face).
Primula hopeana
3. On the ridge to the NW of the Lamse La and also on the lower ridge of Durshingla Sherriff found a plant he thought was Primula strumosa but was later found to be Primula elongata. Primula elongata, P. barnardoana, P. sikkimensis and P. strumosa are all yellow flowered, so you must look to other characteristics to distinguish between these species. In Bhutan two variations of P. elongata occur, having slightly different leaves. What to photograph if you see this species? The most important image is a leaf study! The flower tube is also important to determine this species (side of the flower).
Primula elongata
4. On the high hills and passes surrounding the Pobsikha valley and lower on the ridge of Durshingla grows Primula whitei. The type location for this species is the nearby Pele La. This is another problem species as it is close to or the same as Primula bhutanica. See this blog post for details. What to photograph if you see this species? Any population of P. whitei should be checked to see if plants have any characteristics of P. bhutanica in particular the calyx (side of the flower). A leaf study, especially of the older leaves, would be useful.
Characteristics of P. bhutanica. Can you find plants like these in a population of P. whitei?
5. Another species in the Petiolares section was found growing in this area (Lamse la, Lao La). It caused Sherriff a lot of confusion as he thought it might be P. boothii, but it was later identified as Primula bracteosa. The Flora of Bhutan has P. boothii as a synonym of P. bracteosa, but there is a distinction between the two in that P. bracteosa develops leafy bracts among the inflorescence as it goes into fruit. In flower, the two species are indistinguishable though it is said that P. boothii does not have farina and has a slightly different calyx. What to photograph if you see this species? It is best if the same plants can be visited in flower and in fruit. The calyx detail and any farina should be photographed. A leaf study of the plants in flower and in fruit, including the later leaves in the inflorescence is necessary.

Primula bracteosa,
courtesy Royal Botanic Garden Edinburgh
6. The first Primula encountered by Sherriff on the way to Durshingla was Primula flagellaris, which he found within a mile of Chendebi, on the right side just before cliffs, on the way to the Lamse La. This has been a problem species because it has also been considered a variety of Primula tenella. The distinctions between P. tenella and P. flagellaris are in the flower size and color, number of flowers per scape (1 or 2), presence or absence of bracts and presence or absence of stolons. I believe the species described in 2004 as Primula rebeccae is a synonym of Primula tenella. What to photograph if you see this species? Both a flower study to show size and color variation and a leaf study (both surfaces) with measurements would be helpful. Images of the stolons (runners) and the new plantlets that form on the ends of the stolons. Flower stalks should be checked for bracts (which look like a tiny leaf) and photographed if found. Sherriff believed there was an altitudinal difference between the two species, with P. flagellaris at a lower altitude than P. tenella. It would be exciting if P. tenella was found at higher elevations on Durshingla.
Primula tenella usually has 1 flower and a bract.
If you are at Chendebi, look for a small species on the near by hills (SW) for Primula erythrocarpa which looks like P. atrodentata or a small P. denticulata. Check for basal scales under the leaves and show the hairs on the leaves.

Other Primula species found on Durshingla: P. atrodentata, P. munroi, P. calderiana, P. megalocarpa, P. waddelli, P. bellidifolia, P. obliqua, and P. glabra.

I am uncertain of the exact location of Nabzi La on Durshingla. If you have the GPS coordinates for it or a GPS track for the route up the ridge, please contact Pam. If you are interested in more details of these species or locations, or if you have images of these species, please contact Pam.

A video of Foresters in Bhutan

Pam Eveleigh © 2017

Spring is here, almost (Primula denticulata)

This blog post was originally written over 3 years ago! Though it is now late in 2020, and the pandemic is still with us, looking ahead we can hope that life returns to normal soon. Primula denticulata is surely a wonderful symbol of that hope.

One of the most photographed Primula in the wild is the showy and locally abundant species, Primula denticulata. It is distributed across the Himalaya from Afghanistan through to Sichuan, but it was first collected in Nepal. It was described in 1805 by James Edward Smith and the original description includes a painting. The type specimen LINN-HS 271.2.2  (Herb Smith) was collected by Dr. Buchanan and resides at the Linnean Society. The type location is "the moist parts of the hills about Chitlong in Nepal, flowering from February to April". Buchanan's journey is detailed in "An Account of the Kingdom of Nepal", written in 1819. Chitlong (27°38'59.27"N 85°10'12.17"E) is very near to Kathmandu, though overlooked by plant enthusiasts as they head for more popular trekking areas.

Primula denticulata color forms 
 This species varies across its distribution and authorities have disagreed on the distinctions, creating numerous species which have since been lumped into P. denticulata including P. adenophora, P. aequalis, P. alta, P. cyanocephala, P. harsukhii, P. hoffmeisteri, P. limnoica, P. paucifolia, P. platycrana, P. sinodenticulata, and P. telemachica. A one time even P. capitata and P. erosa were thought to be synonymous. Primula cachemiriana, described from cultivated plants, persists as a name given to plants covered with dense yellow farina. Adding to the confusion are dwarf states which resemble P. atrodentata but can be distinguished by the presence of persistent basal bud scales which were once part of the winter resting bud. 

P. denticulata basal scales flatten to reveal true leaves and flower buds

  Many garden selections have been made. The compact flower heads are composed of numerous erect flowers in shades of purple, pinkish-purple, reddish-purple or white. It is winter hardy in my garden in Calgary, Canada though it does resent water around the resting bud in winter. It is easily grown from seed, which is produced in copious amounts and can be vegetatively propagated by splitting crowns or by root cuttings.

Masses of plants in Bhutan
Pam Eveleigh © 2020