Journal archives for August 2022

August 30, 2022

I casually rant about the differences between Zizotes Milkweed and Silverleaf Nightshade

Zizotes milkweed and Silverleaf nightshade. They look very similar, especially with the wavy leaf margins, fine hairs on the stem and leaves, etc. Doesn't help that they grow around the same time either.

Zizotes Milkweed has opposite leaves, typically coming out at right angles compared to the lower pair. The stacked leaves will create a cross shape:

The cross shape is best seen when looking from above

Silverleaf Nightshade has alternate leaves, which go at angles of 60 degrees or something like that. It also has little thorns on the stem.

See, no crosses!

Leaves on Silverleaf Nightshade tend to be long and thin-ish, like a lance - lanceolate leaves. Those of Zizotes can be lanceolate but are more often oval or ovate.

Some other factors to account for: Zizotes milkweed can take on a reddish/purplish tint sometimes, on the veins or even the entire leaves... I have not seen this on Silverleaf nightshade. Silverleaf nightshade has thorns on the stem, while Zizotes is unarmed.

Lastly, the wavy edge (undulate margins) of Silverleaf Nightshade are very regular/organized... Each "tooth" is about the same size, and not super wavy.
Zizotes margins have no rhyme or reason - they can be there, or not. They can be big undulations, or small ones. Overall, the leaves are very chaotic.

From left to right: not wavy. very wavy. something in between?

The unbelievably variable morphology of this species makes it the hardest species of milkweed to identify (when not in flower, of course)... But there are always clues on every plant that will lead you to the money. It just takes experience.

Zizotes Milkweed will rarely occur in large groups, and rarely blooms in swarms like Antelopehorns, but don't underestimate its hardiness. In a way it is perhaps the weediest of our milkweeds, and if you stare hard enough, it will appear almost anywhere.

Posted on August 30, 2022 08:28 PM by arnanthescout arnanthescout | 5 observations | 0 comments | Leave a comment