A Prickly Subject

I admit that I was initially stumped by the aster I found growing in the Courtenay Airpark. I took some photographs of the plant and was particularly struck by the distinctive row of spines down the midrib of the leaf and figured that this would be an easy one to identify – with a leaf like that I assumed that the field guides would definitely use it as a field mark.

Prickly Lettuce (Lactuca serriola) Leaf
The line of spines down the midrib of this Prickly Lettuce (Lactuca serriola) leaf is an obvious field mark.

An initial look through Pojar and MacKinnon’s Plants of Coastal British Columbia turned up a couple of possibilities but nothing really fit. I thought that the flowers sort of looked like they belonged to the hawkweeds (Hieracicum sp.) but the leaves didn’t fit with any of the common plants in this genus. Instead, I thought that the leaves looked more like sow-thistle leaves (Sonchus sp.) but the flowers didn’t work with any of those species. I’m not great at keying plants out (my wife Jocie has much more patience for it) but thought that I’d try our copy of the Illustrated Flora of British Columbia but was quickly overwhelmed.

Prickly Lettuce (Lactuca serriola) Flowers
Prickly Lettuce (Lactuca serriola) flowers lack disk flowers.

Back to the photographs. I looked at the shape of the leaf and tried to ignore the nasty looking spines down the rib of the leaf and had a thought – the leaf sort of looked like Wall Lettuce (Lactuca muralis) in shape. I returned to Plants of Coastal British Columbia and read through the notes  for this species (often similar plants are described in this section even though an image isn’t usually provided). Sure enough, one of the species described was Prickly Lettuce (Lactuca serriola)! A quick check of eFlora, British Columbia’s on-line database of plants confirmed that my aster was indeed Prickly Lettuce – mystery solved!

Prickly Lettuce (Lactuca serriola) Leaf
The pinnate lobed shape of the leaf of Prickly Lettuce (Lactuca serriola) is somewhat similar to the leaf of Wall Lettuce (L. muralis).

This distinctive looking plant is one more introduced species from Europe that can be found at the Courtenay Airpark Lagoon. The leaves have a network of veins with a very noticeable line of spines down its midrib. The yellow flower consists of ray flowers only – no disk flowers are present. While Wall Lettuce is considered edible, if bitter, I’d have serious doubts about trying Prickly Lettuce!

5 comments

  1. It’s a great resource – essentially the Illustrated Flora of BC on line with the added benefit of photographs of each plant. Each plant has the Flora write-up and line drawings, a representative plant photograph, and links to additional plant images in the gallery. It’s fantastic for double checking plants!

  2. Pingback: Dave Ingram's Natural History Blog :: Raddish Riddle

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