A Gardening Journal

Good Together: Siberian Cow Parsnip, Purple Osmanthus, Chinese Tulip tree

Siberian cow parsnip is another of my garden's immense and dangerous plants, and shares with hardy orange the ability to send careless humans to the emergency room. The danger with hardy orange is its immense thorns, which are long enough and sharp enough to stigmata a hand or puncture an eye. Siberian cow parsnip causes injury because chemicals known as furanocoumarins that infuse all of its parts. If any cut or damaged portion of the plant touches unprotected skin, the furanocoumarin-laden sap can bring on a dermatitis so severe—blisters! scars!—you'll wish it were just poison ivy. Even contact with undamaged portions of the plant is risky.

 

Osmanthus heterophyllus Purpureus Heracleum sosnowskyi Liriodendron chinense 060617 overall 640B

 

Both plants have ornamental potential that's unique as well as substantial, so I grow them respectfully. I allow the cow parsnip to self-seed under careful supervision, so it can pop up with strategic spareness. This one volunteered in just the right place to partner with both purple osmanthus and Chinese tulip tree.

 

The parsnip's coolest connection to the two isn't the contrast with the its immense jagged foliage, stunning as it is. Nor with the umbrella-sized umbels of white flowers held high out of frame. It's with these purple speckles on its stem.

 

Heracleum sosnowskyi Liriodendron chinense 061017 cropped 640

 

Short white bristles emerge from most of the speckles, making the stems of Heracleum sosnowskyi feel disconcertingly rough if you were unwise enough to touch them. If you brush against a stem even lightly, wash the area of contact with soap and cold water. (Warm or hot water would cause dilation of local skin pores and blood vessels and, so, tend to speed infiltration of the furanocoumarins.)

 

The puzzle with Siberian cow parsnip, then, is appreciating its considerable charms without damaging your health. Stand too far away, and you miss tiny details. Stand too close—especially while in the rapture of discovery of such minutiae as the bristles—and you risk direct contact and the resultant serious harm.

 

With details from gigantic to minute, Siberian cow parsnip is complex enough that it's a show in itself. Not least, it bears the largest leaves of any plant hardy colder than Zone 7: five feet long by four wide. Perhaps its only competitor is the foliage of Aralia elata: over four feet long and two wide.

 

Heracleum sosnowskyi Liriodendron chinense 061017 640 

 

Such oversized details are visible from afar; it's the smaller details that tempt you closer. Those speckles, say. Their hue nearly matches that of the young foliage of Chinese tulip tree immediately in back.

 

Liriodendron chinense Heracleum sosnowskyi 061017 cropped 640

 

Although the color repeats, tulip tree foliage to cow parsnip stem, the texture of the stems of Heracleum sosnowskyi—bristling and, literally, untouchable—could hardly be different from that of the foliage of Liriodendron chinense. Its foliage is so smooth and rubbery you might want to place one hand beneath a leaf to steady it while you gently stroke or even pat it with fingers of your other. Plus, you'll want to measure this tulip tree's foliage against your forearm. Leaves are much larger than for our native tulip tree and, often, a single one can extend from elbow to fingertip.

 

To the front of the cow parsnip, and much lower, is a purple-leaved osmanthus.

 

Osmanthus heterophyllus Purpureus Heracleum sosnowskyi Liriodendron chinense 060617 overall 640

 

The young foliage of Osmanthus heterophyllus 'Purpureus' was nearly tar-black when it emerged in early May. By now, it has mellowed to burgundy; by mid-summer, it will have matured to green. For the meantime, it also matches the purple of the heracleum's speckles.

 

Osmanthus heterophyllus Purpureus Heracleum sosnowskyi Liriodendron chinense 060617 cropped 640l

 

The cow parsnip will have set seed and died by August, but in spring and early summer, the juxtaposition of the small, sharp, shiny burgundy foliage of the osmanthus with the oversized green leaves and bristly purple stems of the cow parsnip couldn't be stronger.

 

Cow parsnip doesn't form tall speckled stems its first year; only in the second (or third) do they erupt. Massive flower umbels tip each stem. Below, the nascent flowering structure as it appeared two weeks ago. It was as large as a grapefruit, and was still enfolded in huge pale bracts from which the last of the jagged leaves were emerging.

 

Heracelum sosnowskyi developing umbel 061017 640 

 

Huge and mysterious, this "Now what?" stage in the life cycle of Heracleum sosnowskyi only enhanced its unsettling character. If any plant could have inspired the creature in "Aliens," this would have been it.

 

Two weeks later, the remarkable array of dinner-plate-sized umbels were in place. Hundreds of tiny white flowers are favorites with small pollinators such as flies, wasps, and gnats. Bees and butterflies are much less tempted.

 

Heracleum sosnowskyi umbel 061817 640

 

Look just below the now-fully-opened pale bracts. The purple speckling of the stem there is decreased from that farther down. Above the bracts, the stems that are nearly speckle-free terminate in the umbels. Such stalks that directly support a flowering structure are known as pedicels.

 

Heracleum sosnowskyi stems w decreasing speckling 061817 640

 

With an eight-foot stepladder nearby, the sui generis scale of Siberian cow parsnip is stunningly clear. Its entire complex of umbels is four feet across, and is held nearly ten feet high. Even from this distance, you can see how the main stem has become lighter and lighter—less and less purple-speckled, in other words—with increasing height. This effect, then, isn't just because higher portions of the stem receive more direct light.

 

Heracleum sosnowskyii from bedroom 062017 640

 

By August, the cow parsnip will have died. By then, the foliage of the tulip tree will, like that of the osmanthus, have matured to green. The multivalent combination these three bizarrely beautiful plants are now creating—purple with green, rough with smooth, big with small, benign with downright dangerous—will have vanished. 

 

 

Here's how to grow a more well-known cultivar of osmanthus, Osmanthus heterophyllus 'Goshiki'. It is noticeably hardier in southern New England, so can be sited with a bit more exposure to winter wind; otherwise, its handling & culture are similar to those for Purpureus.

 

Here's how to grow Siberian cow parsnip.

 

Here's how to grow Chinese tulip tree.

 

 
 
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