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 real Primula involucrata (P. boveana)

In a previous post, I talked about why the species called Primula involucrata by many people should actually be called Primula munroi. This is due in part because the names in Wallich’s catalogue are considered “nomina nuda” (therefore invalid), and in part because Sweet used the name P. involucrata for a different species between the time of Wallich’s catalogue (1828) and the time the name P. involucrata was properly published for the Wallich species (1844).

The Sweet publication is "Hortus Britannicus: Or a Catalogue of Plants Cultivated in the Gardens of Great Britain (1839),
page 562" which is shown below. The abbreviations used are listed at the beginning of the publication.

The Sweet species is described as being “ye” (yellow flowered), involucred, from Egypt, “1826” (year introduced into cultivation), “3.4.” (flowering from the third to the fourth month of the year), “F” (requires a frame, not quite hardy), “symbol” (herbaceous perennial), and figured in Curtis’s Botanical Magazine, t. 2842. The abbreviation “L.O.” is given as the source for the information and this refers to “Link et. Otto, Abbildungen und Beschreibungen seltener Pflanzen im Berl. Garten. Berlin 1828 t. 51”.
The synonym given is “verticillata B.M. non Vahl. nec Forsk.” This reads as P. verticillata in Curtis’s Botanical Magazine (t. 2842 (1828)), which is not the P. verticillata described by Martino Vahl (in Symbol. Bot., I, 15 t. 5 1790) and not the P. verticillata described (considered the original description) by Pehr Forsskål (in Fl. Aegypt.-Arab. 42. 1775), so essentially a species previously lumped under the name P. verticillata is being split out as a new species called P. involucrata.

The discussion of the plant figured in Bot. Mag. T. 2842 talks about a plant received in 1825 from Otto of Berlin as P. involucrata marked “AEgypt” but it “suffered so much on the way that it could not be preserved”. The plant figured was grown in Edinburgh from seed obtained from Berlin and it was then compared with P. verticillata of Forsskål (from Arabia Felix which is present day Yemen) and Vahl, from which it was concluded it didn’t differ significantly.

The description given in the Link & Otto reference says the seeds came from Ehrenberg (which would be Christian Gottfried Ehrenberg, a professor at Berlin University, who travelled with Wilhelm Hemprich to the Middle East including Egypt in 1820-1825). The collection location was Mount Catherine, close to Mount Sinai.

Pam Eveleigh on Mount Catherine in 1992
There is only one Primula which grows on Mount Catherine and the immediate area and that is an endemic called Primula boveana. The original description for P. boveana is Decne. ex Duby in DC, Prodr. 8:35 (1844), and the description references "P. involucrata Sweet cat. p. 562,non Wall., P. verticillata Bot. Mag. t. 2842, Link & Otto abb. t. 51, non Forsk".

However the Sweet catalogue was published in 1839 which gives the name P. involucrata priority over the Decne. name of P. boveana published in 1844. 

At the time of the publication of the name P. boveana in 1844, the names in the Wallich catalogue would have been considered valid and so the name P. involucrata Sweet would have been invalid because the name was already taken by Wallich, thus allowing a new name of P. boveana to be created for that species.

At the time of the writing of this post, the IPNI website was not current for this information. (later note: INPI has now been updated).

Additional reading about P. involucrata (as P. boveana):

1. Smith & Fletcher, “
The Genus Primula: Sections Cuneifolia, Floribundae, Parryi, and Auricula”, Trans. Roy. Soc. Edinb. 61:631-686. (1949). Smith and Fletcher considered boveana and simensis as subspecies of P. verticillata, based on limited material.

2. Richards & Eveleigh, “Four name changes in Primula”, in Alpine Diary, The Alpine Gardener, Vol. 80, No. 2, June 2012.

3. Mansour, et. al., “
Development of 13 Microsatellite Markers in the Endangered Sinai Primrose (Primula boveana, Primulaceae)”, Applications in Plant Sciences 2013 1(6):1200515

4. Jiménez, et. al., “
Low genetic diversity and high levels of inbreeding in the Sinai primrose (Primula boveana), a species on the brink of extinction”, Plant Systematics and Evolution , May 2014, Volume 300, Issue 5, pp 1199-1208.

5. Omar, “
Assessing the Conservation Status of the Sinai Primrose (Primula boveana)“, Middle-East Journal of Scientific Research 21 (7): 1027-1036, 2014.

6. Omar & Elgamal, “
Reproductive and Germination Ecology of Sinai Primrose, Primula boveana Decne. ex Duby”, Journal of Global Biosciences , Vol. 3(4), 2014, pp. 694-707.

Primula involucrata or Primula munroi?

There has been confusion over the names P. involucrata and P. munroi for a long time and currently both names are used. So which is the correct name? The problem starts with Nathaniel Wallich, a Danish botanist who collected extensively in India, Nepal, West Hindustan and lower Burma. Wallich compiled a catalogue of plant specimens collected by him and others of the time and this is known as the “Wallich catalogue” and his specimens are housed at Kew and Calcutta (CAL), with duplicates at other herbaria.

Unfortunately all of Wallich’s names in the catalogue are considered “
nomina nuda” and invalid, except where also published separately by him or other botanists. Wallich’s catalogue is available at the Biodiversity Heritage Library and catalogue number 7107 (compiled 1828) is P. involucrata. This would be the first published occurrence of the name, if it were not that it is invalid. The next validly published occurrence of Wallich’s P. involucrata is Duby in Prodromus [A. P. de Candolle], 8:42, 1844. Here a full description of P. involucrata was made and Wallich’s list number 7107 is referenced. This would then make Wallich’s species valid if not for one little problem.

In Sweet's Hortus Britannicus: Or a Catalogue of Plants Cultivated in the Gardens of Great Britain (1839) on
page 562, there is a valid description for P. involucrata, citing that the plant is yellow flowered, involucred, from Egypt and figured in Curtis’s Botanical Magazine, t. 2842 (1828). The species described is not the same as Wallich's plant. Sweet's valid description predates the Duby publication and so the name P. involucrata was not available to be used by Duby and therefore P. involucrata (Duby) becomes a later homonym of P. involucrata (Sweet).

The next validly published description for Wallich’s species was P. munroi, made by Lindley in Edward’s Botanical Register, 33,
t. 15 (1847). So P. munroi becomes the valid name for the species we are all so familiar with.

P. munroi subsp. yargongensis (L), P. munroi subsp. munroi (C), P. munroi subsp. schizocalyx (R)
There are two subspecies associated with Primula munroi: P. munroi Lindl. subsp. schizocalyx Balf.f. ex S.K.Basak & Maiti and P. munroi Lindl. subsp. yargongensis (Petitm.) D.G.Long. The subspecies schizocalyx is distinguished by its calyx which is split to the base and is only found in Northern Sikkim. The subspecies yargongensis was originally described as a distinct species with dark purple flowers from the Zamba La (Sichuan) which would distinguish it from P. munroi subsp. munroi which is white. However images from the wild of populations in the Eastern part of the range (Yunnan, Sichuan) and from the Western part of the range (Nepal, India), show that the flower color can vary from white to purple in both populations. The Flora of China gives the tube length as being marginally longer than the calyx in subspecies yargongensis, but it could be that this distinction varies and may not be enough to warrant subspecies status.


My Camera has the Blues

Color is a tricky thing when describing and photographing flowers. Not only do people differ in their understanding of what is meant by color terms, our cameras “see” colors in different ways than we do.

Primula nanobella color variation.
Words used to describe the most common range of Primula flower colors include violet, blue, mauve, lilac, pink, pinky-violet, blue-violet, amethyst, rose, violet-blue, claret-red, red, wine, purple-blue, purple, magenta, crimson, salmon, magenta-crimson, rose-crimson, rose-purple, lilac-mauve, and rosy-purple. It’s hard to figure out these colors unless you can compare them side-by-side.
Ah, but we can take a picture of a Primula flower described as “lilac-mauve” and that will show precisely what is meant! Well, except there are problems with how colors are reproduced in an image.

Light has a color temperature, measured in Kelvin (K). Numbers over 5,000 K represent the cool, blue end of the scale and less than 3,000 K represents the warm, red end of the scale. Often when we speak about color temperature in relation to digital cameras we talk about the white balance.

Most cameras have pre-sets for white balances such as “sunny”, “cloudy”, and “auto” which tells the camera what color temperature to expect in the scene so that the color can be balanced back to neutral. On the “sunny” setting more blue is added to the image, and on “cloudy” more yellow is added. If you have your camera on the wrong setting you will get a strong color cast to your image (which can be used creatively). In the image below, the same Meconopsis has been photographed with different white balance settings. The left image has a slight blue color cast, and the right image has a strong yellow color cast. Without the visual clue of the background to help us see the color cast, we could think the flowers in the images were different colors.
Same plant with different white balances
The camera model used to take images can also cause problems with color. Camera manufacturers add internal infrared blocking filters to their cameras to add clarity to images. This also cuts out some of the visible red in images so Primula flowers can turn from violet to blue depending on the camera used. Fortunately software can be used to correct for this, but this requires some knowledge of the actual flower color or knowledge of the camera and how it represents colors.

Two cameras record the same species differently

Primula Fertility and Seed Set

A feature of primulas is their heterostyly nature. Almost all Primulas have a pin form (where the level of the stigma is above the anthers) and a thrum form (where the level of the stigma is below the anthers). A few species are homostyle (where the level of the stigma and anthers are equal). Often homostylous species are self-fertile, but for the majority of Primula species, the best seed set is between pins and thrums. When planting out, group at least three or more seedlings to ensure you have both types growing together to encourage seed production . Hand pollination can be used to increase your seed harvest.

Why do you get better seed set between Pins and Thrums?

Primula heterostyly is controlled by a supergene which is a group of neighboring genes on a chromosome which are inherited together. Different loci on the same supergene control style length, anther height, pollen size and papilla size on the stigma. Pin x pin and thrum x thrum mating rarely produce seed due to
incompatibility (see also) between the pollen and style which differ in the two morphs. Occasionally cross over occurs between the genes and two complementary kinds of homostyle, long and short, are formed, with the stigma characteristic of one type and the pollen characteristic of the other, allowing self-fertilization to happen. Note that Primula are protogynous, that is the female stigma is receptive well before the male pollen is mature which is another barrier to self-fertilization.

See also Growing Primula From Seed.