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

Read More

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 https://leythro-darlo.blogspot.ca/2017/02/conservation-journey-video.html

Pam Eveleigh © 2017

Read More

Primula pulchra - Hide and Seek with P. gambleana

In 1882, An article was published in the Journal of the Linnean Society titled "On some Undescribed and Imperfectly known Indian Species of Primula and Androsace" by George Watt. It was actually J.D. Hooker that wrote this article in Watt's name, using Watt's notes, though revising them where needed, and with the intention that this would be used in the Flora of British India that was being written at the time by Hooker.


Primula pulchra or not? (Smith collection)

The first new species of Primula described in the article is P. gambeliana (a spelling mistake of P. gambleana) from a collection (Watt 5483) made at "the Tra Cha Kumpa Kubra Rock (Black Kabur?) above Jongri (Dzongri), Sikkim 27°30'29.99"N 88° 9'9.45"E. It grows in moss and often in crevices of steep wet cliffs.

P. pulchra is the second new species described in the article, from a collection (s.n. 12,000 ft) made by Hooker at Lachen, Sikkim (27°43'2.18"N 88°33'29.02"E, probably in the Zemu valley according to Hooker's Himalayan Journals). Also noted is a syntype collection (Watt 5406) made at the upper Ratong Chu Basin, Jongri (27°32'38.68"N 88° 8'4.47"E) for which Watt 5268 is given as equivalent. This location is very close to the type location for P. gambleana.

Both of these species are figured: P. gambleana - Tab I, and P. pulchra Tab II. A (see image below). Hooker makes the comment under P. gambleana in the Flora of British India: "petiole not sheathed at the base as in P. pulchra, which this a good deal resembles".

Drawings from the Journal of the Linnean Society

If you compare the two drawings side by side, there are a lot of similarities between the two species. Both having a sheathing base, but the scales are much larger in P. pulchra. The most obvious difference is the leaf shape with the leaves of P. gambleana shown as orbicular though Smith & Fletcher later described them as "ovate-cordate or ovate-oblong rather than orbicular" and noted that the figure shows the leaves as more orbicular than is usual. The leaf base is described as usually deeply cordate but occasionally truncate. Smith & Fletcher describes the leaves of P. pulchra as oblong to ovate-oblong with a rounded or slightly cordate base. Both species are shown with an obvious scape with 1-10 flowers. The relative size of the plants on the types specimens are similar.

P. pulchra? capsule (L), P. gambleana capsule (R)
courtesy Royal Botanic Garden Edinburgh

Apparently, the most distinguishing feature is the seed capsule which was not known when the two species were described. P. gambleana has a cylindrical capsule, twice as long as the calyx and dehiscing by longitudinal valves. Seen in only one collection of P. pulchra (Tari, Sikkim, no collector) at Edinburgh is a subglobose capsule equalling the calyx dehiscing by a crumbling wall (Section Petiolares type). This collection is of 6 thin, sparsely flowered plants, and none show the sheathing base that is seen in similar plants in the type collections. Is this really P. pulchra in seed or is it another petiolarid species?

Primula sp Yak Desha = P. pulchra Smith?

In about 1985, George Smith made a collection from the area near Kanchenjunga that was identified as P. pulchra. It was awarded a PC in 1991 and may still be still in cultivation. This clone does not seem to produce the tall scapes of the type collection and it makes me wonder if it really is P. pulchra. In addition to this is a recent image from Yak Desha, Nepal which seem to equate to the Smith collection but again does not seem to be the same as the type collection of P. pulchra!

Perhaps the Smith collection is true P. pulchra, but it is important to get it right because it affects other related species P. chamaethauma and P. chamaedoron which have been lumped into P. pulchra by some authorities.

What is needed is lots of images, including the capsules, of both P. pulchra and P. gambelana from Sikkim in the Ratong basin (near HMI Base Camp) and the cliffs around Black Kabur, near Dzongri and also the Zemu valley. Only with this additional information can this puzzle be solved. If you can help, please contact Pam Eveleigh.

Pam Eveleigh © 2017

Read More

Photographing Primula in the Wild

Pam Photographing Primula agleniana in Tibet

One of the joys and pleasures of administering Primula World is seeing wild Primula images taken by others while travelling. Not every person is a world-class photographer or owns the best camera equipment, but that doesn't mean their images aren't exciting or useful. Even blurry images taken in poor lighting, can show variation and details of a Primula which can further our understanding of that species. I'm happy to see even one image, but it is always better to see many images of a species. See the Primula World image submission guidelines to see how you can be a part of Primula World. 

There are several key characteristics that when photographed can be helpful in identifying and documenting a species:

Flowers: Since the flower face is the prettiest part of the plant, it is the most photographed. Images can show useful details such as whether the flower is annulate or not, the position of the style, farina presence, hairs in the throat, petal shape and color patterns surrounding the eye. If the flowers are hanging, then don't forget to tilt the flower up to see the face! A thorough study would include splitting the flower open to see inside. It is rare that a single image of the flower face is enough to identify a species.


Flower faces (L to R): P. waltonii, P. bella, P. poisonii

Flowers are usually arranged in an inflorescence and the details of this arrangement and the length of the pedicels (which attach the flowers to the inflorescence) are important. The inflorescence is supported on a flower scape which varies in height and also in texture.

Classic spike inflorescence of P. vialii
with diagnostic red calyces.

Calyx, Tube & Bracts: It is just as important to photograph the back or side of the flower as it is to photograph the front. This shows the calyx, which is the outer most part of the flower (it protects the flower bud) and is composed of 5 sepals. How deeply the calyx is split into sepals and the shape and length of each sepal is very important to see. This view also reveals the floral tube which may vary in length and color. Bracts are modified leaves found at the base of the inflorescence that vary in shape and size.

Calyx, Tube & Bracts:
P. munroi (L), P. longipetiolata (R)

Leaves: It is no surprise that leaves are important in determining a species. They come in a variety of shapes and some species even produce more than one type of leaf during the year. Venation can be seen. Many species have farina on the leaves especially on the lower surface or hairs which may be photographed with extreme close-up lenses. The best leaf images are when a leaf is removed from the plant, with the petiole intact, and both sides are photographed, preferably with a scale.

Leaf studies: P. blini (L), P. advena (R)

Farina: Most Primula species produce farina, a powdery substance that may coat any part of the plant. Farina may be white, cream or yellow and may appear to be absent if washed off by rain.

Glandular hairs secreting farina

Seeds and Capsules: Though it is unlikely that anyone would be able to photograph Primula seeds while in the field, it is possible to do so later. Primula seeds by themselves can not determine a specific species, but it can point to a particular Primula Section.

Primula seeds

Seed capsules can also be used to determine an identification to the Section level. Of course we travel to see and photograph flowers! However, last years seeds capsules may still be present even if all the seeds have been dispersed or perhaps some new capsules are forming. A convenient image to make shows the flowering plant together with the old flower stalk and capsules.

Seed capsules: P. sikkimensis (L), P. calderiana (R)

Habitat and Location: A image of a wider view of the plant in habitat gives us ecological information plus relative plant size and population variation. Knowing the location of where the Primula was photographed in the wild helps me define distribution patterns. GPS coordinates can be determined in the field, or later estimated using Google Earth, but even general locations to the nearest place can help.

P. allionii habitat

Putting it all Together
I'm pleased to see any Primula images, but if you have time, a detailed study like that shown below of Primula boreiocalliantha is the pinnacle of excellence. Even common species need to be documented!

Field Checklist of images:
  

1. Habitat – wide view showing the plants and their environment. Note aspect, moisture, base rock (granitic, limestone) and plant associations.
2. Full plant – with measuring scale to show accurate height (or some indication of size, even if it is a finger or a hand.
3. Leaf study – If permissible, remove a few leaves from several individuals by gently tugging downward from the stem so that the whole petiole remains with the leaf. Observe several plants and chose leaves showing variations. Image BOTH sides the leaves, side by side, with a scale. Take magnified images of any hairs, glands or pits on the leaf surfaces.
4. Inflorescence study – Image the flowers from the back or side to show the calyx, bracts, tube, pedicels and upper scape. Note that pin and thrum forms may have different shaped tubes. Pull back a calyx lobe and document any farina inside.
5. Flower study – Image the front of a pin flower and a thrum flower. If this characteristic is not obvious in the image, then cut a flower in half lengthwise and photograph it. If you suspect the species is homostylous, image several split flowers. If the flowers vary in color and size, and it is permissible, remove a few flowers and image them together with a scale to show relative variation. Tilt up flowers which hang down, to image the face of the flower.
6. Farina – It can be hard to determine farina color from digital images due to color rendition problems and farina reflectivity. Observe and write down the farina color. Make sure your images show which parts have farina.
7. Capsule study – If the plant is in seed or old seed capsules linger from previous years, image the seed capsule. Fresh capsules may be cut in half lengthwise to show the internal seed arrangement. Image the height of the scape with a measuring scale as the scape lengthens when the plant is in seed. If possible, show together the whole plant with old seed scape, and new flowering scape.
8. Leaf rosette – Image the rosette (non-flowering plant is easiest) showing the new leaves unfurling in the center.
9. Resting buds, bud scales - If the plant is imaged in early Spring, or late Fall, image the resting bud, documenting any farina present. If the plant is in flower, pull the leaves back to show any bud scales or a sheathing base.
10. Root/stolon study – If permissible, remove a plant from the ground, and image the colors and structure of the roots. Image any stolons.
11. Fragrance – note the fragrance of the flowers and/or roots and write it down.

* Notes can be written on paper in the field and photographed with the plant. Similarly the display of a GPS can be photographed with a plant if the camera is not GPS enabled.

 Remember: Take as many Primula images as you can....and then take one more!

Pam Eveleigh © 2017

Read More

Recent New Primula Species (2016)

The New Year is a good time to reflect on what is new in Primula. Although I have made a lot of progress on my Original Description Project, the list of all Primula species is a moving target. In particular, there have been several Chinese species discovered. Changes for 2016 include:

Primula persimilis - from the original publication

Primula persimilis G.Hao, C.M.Hu & Y.Xu - Discovered near Luzhou, Sichuan, this species has white flowers with a tawny, hairy calyx. It belongs in Section Monocarpicae and strongly resembles P. tsiangii, but differs in flower color, capsule shape and length of pedicels and calyx.

Primula scopulicola G.Hao, C.M.Hu & Y.Xu - A new member of Section Monocarpicae from Sichuan growing at the same location as P. persimilis. It most closely resembles P. lithophila which also grows in the same area but has smaller flowers, distinctly petiolate leaves, a campanulate calyx, and the capsule is globose (not cylindrical).

Primula undulifolia G.Hao, C.M.Hu & Y.Xu - A new species from Hunan, named for the wavy and shallow undulations on the leaf margin. It is a member of section Carolinella which is noted for its calyptrate (opening by a lid) capsules and is similar to Primula kwangtungensis but differs by its smaller flowers and narrowly oblong leaves with an undulate margin.

Primula wawushanica G.Hao, C.M.Hu & Y.Xu - This species was listed in my 2015 year end post, but it had not then been officially published. It belongs in Section Petiolares, Subsection Davidii and resembles P. fagosa and P. epilosa but is distinguished by sessile leaves, smaller flowers, shorter scape at flowering and a calyx split to 1/3. See the original description for images.

Primula calderiana subsp. bawaii

Primula calderiana Balf.f. & R.E.Cooper subsp. bawaii Bawri, Gajurel & M.L.Khan - Differs from P. calderiana subsp. strumosa (P. strumosa) by having efarinose leaves, the calyx cut slightly deeper into lobes with an cute apex, and emarginated petal lobes. it is unclear how this subspecies differs from P. strumosa var. perlata or the yellow form of P. tsariensis.

There are also a series of newly described subspecies published in Primulaceen-Studien, which I don't currently have a copy of. They include:
Primula hirsuta All. subsp. brevipilosa Kress
Primula hirsuta All. subsp. longipilosa Kress

Primula intricata Gren. & Godr. subsp. alpina Kress
Primula intricata Gren. & Godr. subsp. bergidensis (Kress) Kress
Primula intricata Gren. & Godr. subsp. impigrorum (Kress) Kress
Primula intricata Gren. & Godr. subsp. patens (Kress) Kress
Primula intricata Gren. & Godr. subsp. subcordata (Kress) Kress

Happy New Year and Best Wishes to All in 2017!

Pam Eveleigh © 2016

Read More

Primula whitei or Primula bhutanica?

Primula bhutanica

Primula whitei and Primula bhutanica are members of Section Petiolares whose members have a crumbling seed capsule (rather than the seed capsule opening by valves like most species), and often have dimorphic leaves, that is, leaves of a different shape are produced at different times in the season.
There is much confusion regarding these two species and their relationship to each other and, if indeed, they are actually distinct species.

Primula whitei was described first, in 1911, by W.W. Smith from plants collected by J.C. White (#122) on the Pe-le La, Bhutan 27°32'50.33"N 90°12'57.39"E. The holotype is in Calcutta, CAL0000017397, with a photograph of the type at Royal Botanic Garden Edinburgh, E00024821. Many additional collections were also gathered by Ludlow & Sherriff and R.E. Cooper.

Primula bhutanica was described in 1941 by Fletcher who recognised that some plants collected under P. whitei showed consistent, distinct characteristics separate from true P. whitei. Several collections are listed in the description, but the holotype is Ludlow and Sherriff #1166 from the Choling La, in Eastern Bhutan 27°19'22.59"N 91°46'33.69"E and resides at Royal Botanic Garden Edinburgh E00024661.

The distinct characteristics used to separate the two species are: the calyx lobes which are entire (undivided) in P. bhutanica and fimbriated (fringed) in P. whitei, and the corolla lobes which are tridentate (three toothed) in P. bhutanica and crenulate (finely wavy) in P. whitei. Both species are blue with a white zone in the center and a yellowish-green eye. The distribution of the two species is split with P. bhutanica occurring further east than P. whitei.


Characteristics of P. bhutanica

Characteristics of P. whitei (courtesy RBGE)

In fruit the leaves of P. whitei have a base decurrent along the petiole and P. bhutanica has an attenuate base with a narrow, distinct petiole. (see illustration below)

In 1947, L&Ss&E observed and collected under #12299 near Tongkyuk Dzong in Tibet 29°57'39.88"N 94°46'49.59"E a population of plants that had characteristics of both species - some plants had tridentate petals and others had finely crenulately toothed petals. They stated in the field notes: "Specimens under this number should not be separated. All specimens were collected in one spot and represent one species."

From John Richards (Spring leaf left, Fall leaf right)

John Richards has discussed these species in the context of the Section in the article "An Account of Primula Section Petiolares in Cultivation", J. Scott. Rock Gard. Club 15(3):177, 1977. He noted that "it appears that extensive hybridisation has occurred between P. whitei and bhutanica in a few gardens where they self-sow; the majority of plants now in cultivation seem now to be hybrid, with poor pollen and seed fertility."

So only further observations of plants in the wild will help solve this problem.

The Flora of Bhutan keeps the two species distinct but notes that P. bhutanica may only warrant subspecies status within P. whitei.

The Flora of China (1994) reduces P. bhutanica to a synonym of P. whitei with the explanation given in the Chinese version stating that from observations in the wild and the Ludlow & Sherriff collections 12299 and 12291 show the distinction between the corolla lobes and calyx used to separate the two species is mixed in that population.

Pam Eveleigh © 2016

Read More

Sweet Caroline... section Carolinella

Where it began,
I can't begin to knowin'
But then I know it's growing strong

Was in the spring
And spring became the summer
Who'd have believed you'd come along

... Sweet Caroline.*

 

Primula cardioeides in Vietnam

In 1891, Augustine Henry married Caroline Orridge, though their marriage lasted only three years due to Caroline's tragic death from tuberculosis. Henry's job as a Customs officer lead him to Mengzi (modern Honghe) in southeastern Yunnan. By this time he was well established in plant collecting and his collection Henry 10735 from the forests SE of Mengzi was described as Carolinella henryi, named for his late wife. Though it was thought to be a new Genus, Pax later included it within Primula as section Carolinella and the species became Primula henryi. Unfortunately this name had already been used, so it was given the new name "Primula carolinehenryi" by S.O'Brien in the book "In the Footsteps of Augustine Henry". This name has since been corrected according to the International Code of Nomenclature to "Primula carolinehenryae" as it honors a women.

Primula carolinehenryae E00255693
courtesy Royal Botanic Garden Edinburgh

Two additional Henry collections were described from the area around Mengzi under the genus Carolinella: C. cordifolia (now P. partschiana) and C. obovata (now P. rugosa). The distinguishing feature of section Carolinella is the calyptrate capsule (the capsules don't split into 5 valves as most other species do, or by crumbling, but rather have a lid which lifts to expose the seeds). Some authorities recognise subgenus Carolinella which includes this section. The species in the section are distributed in SE Yunnan, S Guizhou, N Guangxi, S Hunan, N Guangdong, and N Vietnam.



P. rugosa, P. kweichouensis, P. wangii from Flora of China

In 2000 the paper "Pollen morphology in Primula sect. Carolinella (Primulaceae) and its taxonomic implications" was published, with SEM images of 7 species. It was found that there was considerable variation in the pollen morphology encompassing all 3 main pollen types (tricolpate, trisyncolpate and polycolpate) of the genus Primula and that this indicated that the group was heterogeneous.

Primula cardioeides pollen
From Pollen morphology in Primula sect. Carolinella (Primulaceae) and its taxonomic implications

In 2010 the paper "Circumscription of Primula subgenus Auganthus (Primulaceae) based on chloroplast DNA sequences" was published. The result of this study was that species assigned to subgenus Carolinella are dispersed among the species of subgenus Auganthus and that as defined, neither subgenus is monophyletic and it is inferred that the calyptrate capsule has evolved multiple times in the genus Primula. Also P. wangii which was initially placed in section Carolinella, but subsequently placed by Richards into section Monocarpicae, has an ambiguous position.

 

In 2015 the paper "Non-monophyly of Primula subgenera Auganthus and Carolinella (Primulaceae) as confirmed by the nuclear DNA sequence variation" was published and it is similar to the 2010 study. It was concluded that the calyptrate capsule has evolved independently at least four times in Primula. P. wangii was found to be close to P. kwangtungensis and P. kweichouensis and so together with P. levicalyx (not sampled) this seems to be a distinct group within the section. In 2014, the species P. hunanensis was described and placed in this group and the following key was presented.

The species presently included in section Carolinella are: P. calyptrata, P. cardioeides, P. carolinehenryae, P. chapaensis, P. hunanensis, P. intanoensis, P. kwangtungensis, P. kweichouensis, P. levicalyx, P. partschiana, P. rugosa, and P. wangii. In future, we can expect that the section will be split to follow the results of genetic study. See the Species Gallery under each of these for more information.



Key (excludes P. hunanensis) from

"Primula calyptrata, a New Species in Section Carolinella (Primulaceae) from Yunnan, China"

* Don't recognise these lyrics? They're from Neil Diamond's "Sweet Caroline"
 

Pam Eveleigh © 2016

 

Read More

Primula lilacina vs Primula bellidifolia (P. hyacinthina)

Primula lilacina

In 2008, Primula lilacina, a new species in Section Muscarioides was described by John Richards. This species is found in Sichuan (Tuer Pass 29°31'0.49"N 100°16'21.09"E and Yading area 28°26'57.86"N 100°20'47.06"E) and features leaves that are densely coated with thick white farina on the underside. It has the typical capitate inflorescence of members of this section though the flowers are relatively large.



Primula bellidifolia in Bhutan

Immediately it recalls the species Primula hyacinthina which was described from Tron, SE Tibet ( 28°19'45.94"N 92°54'11.80"E) in 1936 but which is now included within Primula bellidifolia. This starts ringing alarm bells for me as P. bellidifolia was described as having leaves which are pubescent on both sides and without farina whereas P. hyacinthina has a thick white coating of farina on the under surface of the leaves - just like P. lilacina!

P. lilacina (L), P. bellidifolia (R)

So why are P. hyacinthina and P. bellidifolia lumped together? If we look to the field notes of the Ludlow & Sherriff collection #5635 from the Tse La, Tibet ( 28°49'19.88"N 93°42'33.93"E), they note that though the collection is identified as P. hyacinthina and the leaves have white farina on the underside, a few plants in the population showed no farina on the leaves. In cultivation, some of the leaves on the same plant of P. hyacinthina can be occasionally be efarinose or nearly so and sometimes typical P. bellidifolia produces farina on the petiole and base of the leaves. It seems then that we are looking at a complex of variable plants, and this is seen in the large number of synonyms for P. bellidifolia (P. adenantha, P. atricapilla, P. hyacinthina, P. menziesiana, and P. micropetala), though all of these synonyms except P. hyacinthina are from a localized area in Bhutan. See an explanation by  R.E. Cooper. P. bellidifolia was originally described from Sikkim, but the species as a whole is distributed in a wide area from Eastern Nepal, through Bhutan into Arunachal Pradesh and Tibet (for P. hyacinthina). The type locations for P. hyacinthina and bellidifolia are 420kms apart. The herbarium sheets for P. hyacinthina are E00024548 and BM000996891.

 

What makes P. lilacina different from P. hyacinthina? It is unfortunate that Richards did not compare the two species when he described P. lilacina. The obvious difference  between the two is geography. The type locations for these two species are 750kms apart, and neither species seems to have been found in the intervening territory. In all other characters it seems they are equivalent.

 

Perhaps genetic study of these species will help to determine their relationships, but until we have more information it is expedient to keep P. lilacina as a distinct species. See more images in the Species Gallery.

 

Pam Eveleigh © 2016

 

Read More