Nature Scrapbook: Cardinal flower

A cardinal flower and a hummingbird against a green background By David Byron Keener/Shutterstock

The show-stopping cardinal flower counts on a cottage-country bird for pollination after summer sets in. From late July to mid-September, cardinal flowers stand out in deep crimson along the soggy banks of lakes and slow-moving rivers from New Brunswick to Ontario.

For anywhere from two to five weeks, up to several dozen individual hermaphroditic flowers bloom, a few at a time, along a single, unbranched, knee-high spire, starting from the bottom. Bearing first male, then female parts, each flower makes use of strategic timing to successfully reproduce. 

A newly open flower produces yellow pollen for three to 10 days in a slender, male, brushy-tipped tube projecting from it. Afterwards, a thin, female style emerges from the centre of the tube to receive pollen from other flowers for another two to four days.

In Canada, only ruby-throated hummingbirds pollinate cardinal flowers. Their long, needly beaks reach the rich pools of nectar at the bottoms of the deep tubular beauties. They usually imbibe first at the middle of the floral spire where some female parts are showing and then hover upwards towards the male flowers, which hold the most nectar, at the top. 

Brushed with a strip of pollen onto their foreheads, they then cross-pollinate female-stage blossoms in the middle of the next stem they visit. 

Plants that are pollinated may produce up to 30 dry capsules, which split open in autumn to release thousands of dust-like seeds to the wind. However with most hummingbirds cruising south in late summer, many cardinal flowers never get fertilized. 

Around mid-August, the plants also begin sprouting a ground-hugging cluster of leaves from their shallow roots.  If the plant survives through the winter, it sends up a new flowering stem late the following spring.

After germinating from seed, a cardinal flower usually doesn’t raise a flowering stem until its second spring. The plant seldom lives more than a few years.

This article was originally published in the August 2022 issue of Cottage Life.

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