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


Post a Comment