A nauseous Camassia mass at Kew Gardens

Walking along the Thames Tow Path this morning, the first time since returning from a week in China and two in Australia, I saw why everyone gets so excited about Camassia cusickii*. This is a picture from my phone (looking across white umbelliferous flowers on the Thames side of the ha ha).

This North American bulb is rare in the wild but became easily naturalised in Kew Gardens when planted for this purpose in 2003. Now you can see from the Riverside Walk within the Gardens, or from the Tow Path outside, a lovely sea of blue every May. Before I left, things were just starting:

There are five species of Camassia, all of which form large and conspicuous colonies according to an early review of their taxonomy by Frank Gould. Some species are widespread but contrary to quite a few reports, Camassia cusickii* is restricted to a small region near the Oregon-Idaho State border. In fact Gould in 1942 says it is restricted to the Snake River region in north-eastern Oregon, and not collected from there in recent times (sensu 1942). The only living bulbs seen by Gould came from California, where they were grown without any knowledge of where they came from.

The more recent treatment of Cassia in the on-line Flora of North America suggests a slightly wider distribution, extending into Idaho. Even so, there are only two adjacent dots on the map, so it may be still restricted to what's called Snake River country.

It grows there on hillsides, between 1000 and 2000 metres above sea level, unlike the other species of Camassia which favour wet meadows. Interestingly it's growing in what could be called a wet, or slightly damp, meadow here at Kew Gardens.

The bulbs of common Camassia are eaten by Native Americans, where they are called quamash or camas. The bulbs are roasted for couple of days to sweeten them, producing something a little like a sweet chestnut in flavour. In case you get a hankering for one of Kew's bulbs, I should let you know that Frank Gould describes the bulbs of Camassia cusickii* as 'nauseous, pungent and inedible'.

If you want to see (but not eat!) one of the edible-bulbed species, look out for Camassia leichtlinii in the Rock Garden at Kew, or the Bog Garden at Wakehurst Place.

The flowers of our nauseous-bulbed species are often said to be pale blue and I did read that the cultivar 'Zwanenburg' has darker blue flowers with a pale stripe on each petal. So as this close up shows, I expect we have Camassia cusickii* 'Zwanenburg'. Presumably still with pungent and inedible bulbs...

*Postscript: I was intrigued but not greatly surprised to read a sign erected inside Kew Gardens celebrating the camassia blooms and calling the species Camassia leichtlinii. The rareness of Camassia cusickii in nature and horticulture worried me a little, despite it being listed on our website as the source of this mass planting (see the end of this webpage, under The Species at Kew) and mentioned (albeit with surprise also) in Tony Cope's book on The Wild Flora of Kew Gardens. I note that a more recent page on our website goes further still and lists the species as Camassia leichtlinii subspecies suksdorfii. For more information on this species and subspecies, well take a look at that original page that set me on the wrong track... And when you've done that, go to Wakehurst Place and take a look at Camassia leichtlinii 'Lady Eva Price' (as I did this morning), named after the family who owned the property prior to the National Trust/Royal Botanic Gardens, also featured on that page.