Plant ID Milkweed

(Question)

I found this strange plant growing in my vegetable garden 2 weeks ago. Do you know what it is? It appears alien?

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(Answer)

Dear gardener,

Thank your for your question as to plant identification — always a wonderful challenge! First, you mention this plant is in your vegetable garden; but, of note, the plant appears to be an established perennial, and one that was possibly growing in your garden last year, or even the year before, judging from the size and maturity of the stalks and leaves. Do you recall planting a milkweed, common milkweed (Asclepias syriaca) in your garden in the past few years, maybe a gift, or from a plant swap? Or maybe you have milkweed plants in your radius vicinity that possibly self seeded over the past few years?? Either way, this is what you have, of the family Asclepiadaceae, which is, by the way one of the most sought-after pollinator plants of the decade.

Milkweed is a perennial herbaceous plant, beloved for feeding by monarch butterfly larvae, that propagates via rhizomes. One of the keys to identifying your plant is that the leaves are broad, and lanceolate, and situated opposite each other on the stems. However, milkweed (which name, nowadays is heralded as royalty among  garden perennials, and, in this context, not a ‘weed’ at all) is not without its share of cultural issues, one of them being the bacterial Phytoplasma infection. This bacteria, causing diseases in plants, is transported by insects. On milkweed, the most common couriers are leaf hoppers. Their mouths pierce and suck out the valuable phloem from the plant’s transmission system, and thus the bacteria are injected into the plant. Yellowing of leaf colour, and growth of small, curled, very ‘alien-looking’ leaves follows. To save the plants root systems, and stalks, you can either (1) remove the tops where the miniscule leaf hoppers have resided, and vigilantly watch, by day, by week, for further infestations, or (2) remove the plants entirely, if they appear to be not thriving. (3) I would vote for first cutting back the infested, yellow plant tops, and for good measure, provide good cultural practices for the parent milkweed plants, so that they will be equipped to stave off any future infestations: plenty of good sun (6-8 hours/day), open air circulation to discourage fungus or bacteria from thriving, and work in well-aerated nutrient growing medium, water until moist, and with good drainage, for the horizontally growing rhizomes.

You know, you may even want to consider re-locating your milkweed plants, depending on your vegetable garden options, to achieve this. Either way, you now have the opportunity to save, and restore, your valuable milkweed plants. Thank you for writing.