J. D. Hooker and Primary Data Sources (Primula pulchra)

P. denticulata, a common species near Lachen, Sikkim

The easiest way to investigate a species is to read secondary sources of information. These are often such works as monographs or regional floras. We are now at least one generation removed from some of the prominent explorers and plant hunters of the Himalaya, such as George Sherriff (1898-1967), Frank Ludlow (1885-1972), Frank Kingdon-Ward (1885-1958) and even further removed from such explorers as Joseph Dalton Hooker (1817-1911). When William Wright Smith and Harold Roy Fletcher wrote a series of articles (see bottom of this book list) in the 1940's on Primula, they effectively wrote a monograph of the Genus. This is a secondary source of information, but the great advantage of their work was that they could personally consult some of the explorers. Now that those explorers are no longer alive, we can't ask their opinion on the distinction between two species, or what the wild habitat was like or even the most obvious question : Where exactly did you discover that species?

Joseph Dalton Hooker (public domain)

Secondary sources can be frustratingly vague on that most basic of questions by copying the location given on the herbarium sheet or in the field notes. Often this location is given as the name of the nearest prominent place to the collection site - not where the specimen was actually collected. Such is the case of Primula pulchra (see my related blog post "Primula pulchra - Hide and Seek with P. gambleana". Hooker gave his unnumbered collection as the type of the species and cited the location as "Lachen, 12,000ft", June 8, 1849. Since Lachen is actually at an elevation of approximately 8,700ft, it is obvious that this is not the actual collection location. So exactly where did Hooker make this collection?

Hooker wrote a two part book called the Himalayan Journals about his travels in this area. Unfortunately this isn't a day-by-day account and so we have to piece together his route by reading several pages starting at pg 47 in Volume 2. We find that he was in the Zemu Valley, and camped at the junction of the Zemu and Thlonok rivers at a place we now call Tallem 27°46'50.48"N 88°29'31.50"E which is at an elevation of approximately 10,700ft - still not high enough to be the collection site. On page 50, Hooker tells us that he repeatedly ascended the north flank of Tukcham mountain (now called Lamo Angdang), but that he also went up the Zemu valley, either of which could get him to the correct elevation of 12,000ft.

Looking from Lachen to the head of the Zemu Valley (L side)
Photo: Abhinaba Basu (Flickr, CC)

Luckily we have access to a primary source of data - Hooker's diary and letters from that time. Thanks to Cam Sharp Jones at the Joseph Hooker Correspondence Project, Kew, I was able to read Hooker's diary entries for June 7th and 8th, but it was still unclear as to exactly where Hooker had ascended on June 8th. Luckily, Hooker wrote a letter to Archibald Campbell on June 9th describing in detail his activities on June 8th. Included is a hand drawn map showing his camp spot which is on the south side of the river, not the north side where modern expeditions camp. He describes his ascent of the mountain (Tukcham) to the south of his camp:

"I went up to nearly 14,000ft by a steep torrent, snowed the whole way up i.e. from 11,000ft up to perpetual snow at 13,500ft, which was there continuous and flanked by lofty black precipes wholly inaccessible. The fatigue of the ascent was very great from the snow, slipperiness, and enormous rocks which are constantly tumbling from above."

There is a gully rising up the mountain from Hooker's camp spot and there is no doubt in my mind that this is where Hooker went. There is an image of this gully
on a website detailing a trip up the Zemu. This a dangerous place to ascend and it is a testament to Hooker that he was able to do it without being injured, especially considering the rock fall. It is likely that Primula pulchra will be found in the nearby Kishong La or up the Zemu valley towards Green Lake, so I have hopes that someone will soon take images of this elusive species.

Pam Eveleigh © 2017