Posts Tagged ‘2013 Plant Guide’

Cushion Spurge - Euphorbia polychroma (syn. E. epithymoides) - Prince George, B.C. - May 18, 2014

Cushion Spurge – Euphorbia polychroma (syn. E. epithymoides) – Prince George, B.C. – May 18, 2014 Image: HFN

Perennial. Zone 1. Euphorbiaceae. Native of Europe from southern Germany to the Ukraine, Bulgaria, Greece and Turkey, where it grows in dry forests, mixed meadows, and on rocky hillsides.

Euphorbia was named by Linnaeus in 1753 for Euphorbus, the Greek physician of King Juba II (circa 12 B.C.E.) of ancient Numidia and Mauretania (approximately present-day Morocco), who reportedly discovered medicinal uses for the local species. While Linnaeus assigned the species name epithymoides for this plant, it was renamed polychroma in the 1850s by yet another classifying botanist, Anton Josef Kerner, and this name soon took precedence and is the more commonly recognized designation today. Polychroma is after the Greek polu – ‘many’ – and xrwma – ‘colour’, a reference to the shaded colours of the bracted stem tops and ornate flower clusters.

Sun to part shade; average conditions. This appears to be a deer resistant plant – something to note for those of you afflicted by these increasingly bold and destructive garden pests.

It’s well into May, and everywhere I go these days I note the unmistakably glow of this unique specimen plant. It flourishes happily in mature, well established gardens as much as in newer, more avant-garde plantings accenting newly built homes in the posher parts of town. When (and where) the lilacs bloom, then (and there) too the cushion spurge.

I first became aware of this rather unusual and eye-catching ornamental during our first spring living in an older neighbourhood in a small Alberta town. Many of the front porches of the modest clapboard-sided 1930s’ and 40s’ era homes were flanked by perfectly globular, neon-yellow-tipped twin bushes. Some kind of exotic shrub? – I wondered to myself, until a visit to the botanical garden at the Calgary Zoo acquainted me with its Latin name, and I was able to track it down in the gardening books. (This was long pre-internet – I smile at the memory of how laborious this sort of rather basic research used to be, before the wonders of the Google image search!)

The natural form of this plant is neatly globular, though it may occasionally "birdsnest" with summer thunderstorms. If this happens, a hard trim to within 6 inches or so of the crown will result in quick regrowth to tidy cushion shape.

The natural form of this plant is neatly globular, though it may occasionally “birdsnest” with summer thunderstorms. If this happens, a hard trim to within 6 inches or so of the crown will result in quick regrowth to tidy cushion shape. Image: HFN

Cushion spurge grows to 18 inches tall and 2 ft. wide where happy – which is most places, as it is an adaptable, good-natured thing. It thrives in sun to part shade, and in modestly moist to dry soils, though it doesn’t care for overly soggy ground. Once established it is very drought tolerant, though it will definitely appreciate the occasional soaking in hot summers.

Clumps of woody-based stems are lined with whorls of soft green, rounded foliage, which are tipped with the modified leaves commonly referred to as bracts, though the correct term in this case is cyathium leaves. These turn a vivid, glowing, chartreuse-yellow, centered with clusters of tiny, even brighter yellow petal-less florets. These clusters include nectar-rich glands – nectaries – which reward foraging pollinators. I have not noticed that bees are particularly attracted to the blooms – though they do visit – but the highest traffic seems to be small flies, and ants and other crawling insects.


Note the small visitor. Image: HFN

An even closer view showing flower structure, and the downy hairs which give the entire plant its velvety texture.

An even closer view showing flower structure, and the downy hairs which give the entire plant its velvety texture. Image: HFN

After blooming and pollination – peak bloom time is all through May and into June – the yellow colour fades to a uniform green. Seed capsules form which eventually pop open later in the summer, catapulting seeds out into the garden, where they sprout in modest numbers. Seedlings are easily removed or transplanted to more desirable locations, where they quickly settle down to the business of growing and forming yet another perfect little globe.

Cushion spurge remains attractive through summer, and can be left to fend for itself or clipped back to produce fresh foliage. The plant fades to yellow in the autumn, frequently showing a red stage before the leaves finally wither after the last, hardest frosts.

Several “improved” (or perhaps one might say “enhanced”) cultivars of Euphorbia polychroma are popular in the nursery trade, including the burgundy-blushed ‘Bonfire’, a patented selection of the Euphorbia polychroma ‘purpurea’ sport which has been grown as a desirable rarity for many years, sometimes under the cultivar name ‘Candy’, and the white-pink-green ‘First Blush’. Of these two types I much prefer the red-leaved variety, as I’ve noticed that the white-variegated form is much less vigorous, and seems to show a high percentage of deformed and puckered leaves.

Euphorbia polychrome 'purpurea' - red-leafed form - an excellent specimen plant, more restrained and smaller than the green-leaved original.

Euphorbia polychrome ‘purpurea’ – red-leaved form – an excellent specimen plant, slightly more restrained and measurably smaller than the green-leaved original. Hill Farm, May 21, 2014. Image: HFN

E. polychroma 'purpurea' shows its richest dark red shading just before the yellow bracts fully develop; after blooming it fades to a uniform green.

E. polychroma ‘purpurea’ shows its richest dark red shading just before the yellow bracts fully develop; after blooming it fades to a uniform green. Image: HFN

The common form of this handsome plant is a venerable garden old-timer, having been grown for centuries both for ornament and for occasional medicinal use. John Gerard’s masterwork The herball, or Generall historie of plantes, first published in England in 1633, reported of  Spurge that “…the juice or milke is good to stop hollow teeth…”  A modern commentator theorizes that the poisonous latex probably destroyed the nerve endings. The specific species of Euphorbia referred to is unknown, though all share the same milky (and irritating) sap. 

Another medicinal use, and the origin of the common name of this very large genus (over 2000 species, found worldwide), is that of a purgative – a vigorous laxative – though one that was prescribed with some caution, as the violence of its action could be fatal if the decoction was too strong. From the French medical term describing the process, “espurgier”, came  the English “purge”, and hence “spurge”, or so the theorizing goes. Though we no longer find ourselves partaking of the plant in any way except that of enjoying its attractive appearance, it is a good idea to treat the plant with sensible respect.

The sap of some species was used to beautify the complexion, and to remove warts, but the herbalists warned about the dangers of letting it get into the eyes, as it could cause severe damage, even blindness, a caveat which has been brought forward to the present day. Some people experience a skin rash from handling the cut foliage, so it is best to be on the safe side and use gloves while pruning. Avoid contact with the milky sap, and supervise young garden visitors if they are too young to heed “don’t touch” warnings.

Don’t let this last bit about the fearsome qualities of the sap put you off – this is a very widely grown plant and incidents of problems with it are exceedingly rare. It doesn’t need much fussing, and can safely be handled with the same common sense that applies throughout the garden. “Don’t put the monkshood leaves in the salad; don’t poke yourself in the eye with the spurge.” There, see how easy that is?! 🙂

One final note. Euphorbia polychroma/epithymoides was awarded the Royal Horticultural Society’s prestigious Award of Garden Merit in 1993, confirming its excellent ornamental qualities to the world at large. Experienced gardeners will have taken this as a confirmation of what they already knew. This is a quietly grand garden plant.



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Vernonia noveboracensis – Ironweed – University of British Columbia Botanical Garden, Vancouver, B.C. – September 2008. Image: HFN

Perennial. Zone 3.  Asteraceae. Eastern North America.

In the months of lavender, late summer

and early fall…

…in the ageing fields

ironweed opens bright fur to nectar moths…

Purple Asters ~ Robert Morgan ~ 1981

My first glimpse of Ironweed at the UBC Botanical Garden in Vancouver left me completely smitten. I’d certainly heard about it before, often recommended as a back-of-border fall-bloomer, but the reality of the eye-popping neon purple and the intricacy of the flower clusters was hugely more appealing than any of the rather washy photos I’d seen.

Vernonia is a huge genus estimated at over 1000 species worldwide. A number of the tropical species are important food plants, producing edible foliage. I have not yet heard of a similar use for any of the more temperate varieties, though a study of ethnobotany would doubtless find culinary and medicinal uses on this continent as well.

Of the 17 Vernonia species documented in North America, noveboracensis is probably the best-known. It is named after the English botanist William Vernon who first collected specimens of the plant in Maryland in 1698. The specific name, noveboracensis, refers to its wide occurrence in the state of New York, and indeed through a large range on the eastern seaboard from Massachusetts to Mississippi. It does not appear to be native to Canada, though it is now widely available from specialist nurseries in this country.

Ironweed’s common name most likely comes from the rusty-red colour of the seedheads. As the vivid purple petals eventually wither and turn brown, clinging to their calyxes, small puffs of rather dandelion-like seed clusters emerge. These are eagerly consumed by chickadees and other small seed eaters, who love to perch on the sturdy ironweed clumps to forage for food and to survey their surroundings from a safe height.

The stems of ironweed are also iron-strong, as one of the UBC gardeners joked to me. This is not a flower to be casually snapped off – pruning shears are definitely in order when harvesting blooms for bouquets. And you will definitely want to do that. The vivid purple tassels contrast perfectly with other fall bloomers; the paler mauve Joe-Pye Weed, any of the Rudbeckia, Echinacea and taller Sedums, late-blooming Phlox paniculata, plume poppy, the Michaelmas daisies and the last of the annual sunflowers all combine to make a sweetly fragrant and long-lasting autumn arrangement.

Ironweed is definitely a wildflower; unkind souls might even dismiss it as rather weedy. Undeniable – I certainly would not place it in a front-row position. At the border back it provides a nice foliage presence to frame more “domesticated” earlier flowers, and, once these are over, a welcome burst of colour to usher in autumn.


A closer look at the bloom clusters. Note the unique “checkering” of the buds. Image: HFN

                         October inherits summer’s hand-me-downs: the last of the ironweed, its purple silken tatters turning brown, and the tiny starry white asters tumbling untidily on the ground like children rolling with laughter…

Rural Free ~ Rachel Peden ~ 1961 

This is a rambly sort of Plant Portrait; I really do like this plant. Perhaps I should concentrate on its garden attributes. Read on! (If you so wish.)

Brilliant purple, sweetly fragrant tassel-flowers emerge from clusters of elongated, geometrically-checkered buds mid-August through September.

Foliage is undeniably rather coarse. Heavy, pointed and lightly serrated 6 to 8 inch long, lanceolate leaves are dark green with paler undersides. THese are arranged alternately along the sturdy stems.

This ironweed is a sturdy clump-former, 4 to 6 feet tall, with a 2 to 4 foot spread. It grows largest on moist soils. It does not run from roots. It may self seed, but is not invasive in my experience.  For shorter, bushier plants, cut back when 24″ tall; new growth will quickly re-sprout and produce double the flowers in late summer on more compact plants.

Handsome in its own rough way, Ironweed is best sited as a back-of-border or wild garden plant. It comes into its own in late summer and fall when the main perennials bloom seasons is over.

Rather similar in effect and garden use to Joe-Pye Weed (Eupatorium) but colour is much more vibrant, being a “neon” shade of bright purple. Blooms fade to red-rusty brown, which is likely the reason for the common name.

A grand bee and butterfly flower, and an important nectar source in late summer. It is visited by migrating hummingbirds as they travel southward. The seed heads may be left on plant to provide seed for wild birds (though this may result in self-sown seedlings next year), or clipped off. Sturdy stems stand up to heavy snowfall; a favourite perch for small seed-eating birds if the seed heads remain.

Oh, and it’s deer resistant.

Widely adaptable to most situations. Likes moisture but tolerant of dryness. Prefers soil on the acidic side, but happily tolerates alkalinity.

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