I hope my readers will allow me another species-based article, this time on one of the largest of all plant families, with about 2,000 members, namely Euphorbia, the Spurges. Some of you might wonder what could possibly be the interest of a whole plant family that is basically green all over. Somewhere, however, in its genetic make-up there must be anthocyanins, the red or reddish colour range, while in others the green is tinged with yellow, white, brown, orange, or even black. Some are huge trees (E. ampliphylla, from the rain-forests of East Africa, can grow to almost 100 feet), some resemble viciously-spined cactuses, or are pebble-like succulents, and we have a scruffy native species: E. peplus, "Petty Spurge" or "Milkweed", a sometimes rust fungus-infested weed about three inches high - hardly a pretty sight, and, like all of them, it "bleeds" a gooey white liquid when broken, which can cause some people serious skin irritation, and is toxic to most creatures if ingested: the plant's rather effective defence system. Wearing gloves while handling any spurge is highly recommended, though that liquid has long been used as a folk remedy for such things as warts, and recent studies in Germany found one of its ingredients promising in the treatment of squamous cell skin cancer.
Some shrubby euphorbias can grow to twelve feet or more in their home environment. One such is the Honey Spurge, E. mellifera, with an odd brownish inflorescence wafting honeyed scent in late spring and early summer. In Britain it usually reaches about four feet or so, though there is a really big specimen here in Eynsham, near the corner of Queen Street and Bitterell. I wrote "inflorescence", rather than just "flower", because that part of every spurge is unique to the species. It’s called a pseudanthium, a “fake flower”; the actual flowering parts (of both sexes) are tiny, but are surrounded by brighter structures that attract pollinators, through colour and/or scent. E. mellifera copes with British cold pretty well, though it suffers below about -10, often regrowing from the plant's root-stock below ground. I have a similar one in my own garden, the rather ominously named Euphorbia stygiana, and lost about a third of it a couple of winters ago, but it bounced back excellently.
More familiar is E. characias or its subspecies "wulfenii", both of which also grow to about four or five feet. Characias has almost black nectar glands around its tiny flowers, which sounds grim, but is actually very striking; wulfenii is orange-yellow. For really strong colour the herbaceous varietal E. wulfenii "Fireglow", which has almost scarlet flower heads at about two feet, is one the best available; another I highly recommend is E. rigida, "Stiff Spurge", which crawls around at about six inches, and has acid-yellow flowers from very early in spring, which slowly turn reddish till about June. Like many spurges it seeds about if happy. The "babies" are easy to move if they're a nuisance, but if you want to move a larger plant, make sure the root-ball has plenty of soil attached, or it will just sulk or even die, however much you try to water it in.
Though most of the above reflect their Mediterranean origin by liking sun and good drainage, there is a very useful exception in Wood Spurge (E. amgydaloides var. robbiae), which really is green all over, but manages to grow AND flower in deep shade, even dry deep shade. It will even grow under a beech tree ... give it some sun, though, and it will glow deep red late in the season as well.
Here I have only been able to “scratch the surface” of the spurges. Having trundled along unobtrusively for years, they recently have become more fashionable, perhaps because growers found forms crossed readily, or even threw up sports, which could be marketed. Some of the new ones are very fine: Euphorbia "Bonfire", for example, with its strong purple colouring and yellow inflorescence, but others might be thought a bit hectic, like the multi-coloured "Ascot Rainbow". Many of the greener ones mix well in a border with strong coloured sun-lovers, like alstroemerias (Peruvian Lily), dahlias, or why not amongst bush roses? Their "flowers" often last for months, many seen to thrive on neglect, and they can add a touch of the exotic to any English garden. Handle with care (the white "goo" is particularly dangerous to the eyes), and they can reward you with years of unfussy display.