Family Members Don’t Always Look Alike

Gardening with Nature

Article by Sigrie Kendrick

Within a genus of plants, there are generally species that can vary significantly from each other in form, size, colour, and other characteristics—and within the species, there are often different cultivars.

For instance, within the knotweed family of plants, Persicaria is a genus that includes many species you might not even recognize as being related.

That’s the case with two of the drought-tolerant plants you’ll be able to purchase at the Okanagan Xeriscape Association’s annual plant sale on May 7, 2022.

New this year is Persicaria polymorpha, also known as Giant Fleece Flower, which features Astilbe-like, creamy-white blooms, which darken to pink and turn a reddish-bronze with the arrival of cooler weather in the fall. If sheared after the first bloom, you will be rewarded with a second flush of flowers.

This spectacular herbaceous perennial reaches heights of six feet with a spread of 6-10 feet and it can be grown in plant hardiness zones 4-9, in full sun to part-sun.

It begins blooming in June and continues throughout summer. Whenever I am working in the Xeriscape Demonstration Garden and this is in bloom, I am constantly being asked where this stunning perennial can be purchased, so I’m delighted that we’ve been able to source it for our sale this year.

In a seven-year trial by the Chicago Botanical Garden of 30 Persicarias, Persicaria polymorpha was the only one awarded four stars and it was judged tops in its field.

Incidentally, Persicaria’s common family name, knotweed, refers to the swelling at the base of the leaves resembling a knot.

A quite-different Persicaria which will also be available at our sale is the diminutive Persicaria affinis ‘Dimity’.

I have featured this Persicaria as Plant of the Month on our website as it is a personal favourite.

Commonly known as Himalayan Fleece Flower, it can be seen growing in the Xeriscape Demonstration Garden in our lawn alternative bed.

As the common name suggests, this Persicaria is a native of the Himalayas and can be found at altitudes up to 15,000 feet.

It features a dense weed-suppressing mat of green leaves accented by red and orange hues.

The flowers of Persicaria affinis are just 10-12 inches high and burst into pink bloom in July, transitioning to shades of pinky-orange and finally fading to a russet hue as the growing season winds down.

This is an extremely long-blooming perennial with all bloom stages and colours present at the same time.

Neither Persicaria polymorpha nor Persicaria affinis are troubled by deer or picky about soil and both are pest and disease-free.

Check out our plant database for more information on these and other xeriscape plants.