I recently came upon an article being shared within a Facebook Group devoted to "Growing Milkweeds" arguing the case for growing non-native Tropical Milkweed (Asclepias curassavica) for Monarch Butterflies. The article was based on the single opinion of one entomologist in accordance to their own observations; in contrast to the multitudes of research that has been done from various institutions and organizations focused on invertebrate conservation, such as the Xerces Society. This online group in particular is focused on growing Milkweeds, not for conservation purposes, but for more of a hobby or as a collector's item and there are many posts showing off various forms of Milkweed both within the Native Asclepias Genus as well as from other foreign Genera such as Old World Calotropis. But this article, was focused specifically on growing Tropical Milkweed out of its natural range as a Host Plant for Monarch Butterflies, in what is becoming known as "Green Washing."
"Green Washing" is the term applied to various forms of marketing for what could only be described as gimmicks, taking advantage of the good-hearted nature lover who is just trying to do right by the Earth. You've seen it with "Pollinator Wildflower Seed Mixes" that contain invasive plant seeds as well as most any "Good for the Bees" campaign which more than likely is only focusing on the invasive yet domesticated livestock known as the European Honeybee; rather than our myriad of native pollinators that, in fact, do much of the brunt work of pollination. Similar Green Washing is done in relation to insect or bee houses, which in turn only bring these solitary species together in densities not found in nature, which allows contagious disease to easily spread within the population. As the Green Washing issue (fueled by capitalism) continues to exist, my argument against growing Tropical Milkweed is simple: What is the point?
Every region within North America has at least 3 different native Milkweed Species to that region. Long Island specifically is home to TWELVE DIFFERENT species of Milkweed including: Butterfly Weed, Common Milkweed, Whorled Milkweed, Poke Milkweed, Green Milkweed, White Milkweed, Swamp Milkweed, Purple Milkweed, Four-Leaved Milkweed, Blunt-Leaved Milkweed, a fertile hybrid between Blunt-Leaved and Common Milkweeds known as Intermediate Milkweed, and even rarities like Red Milkweed. Other regions like the Desert Southwest have an even greater diversity of Milkweed species, again with many becoming increasingly rare in nature. Armed with this knowledge, I say: "Even if Tropical Milkweed does not have a negative effect on Monarch Migration, why spend time and resources cultivating and marketing an exotic plant, as our own native species are left to slowly fade away into extinction?"
In a capitalist society, we Vote with our Dollar, and every time someone purchases Tropical Milkweed they are buying into the same industry that has played a grand part in destroying our ecosystems with the cultivation and marketing of countless invasive species from foreign lands. All of this energy, passion, exchange of ideas, and money could and should instead be focused on preserving our native Milkweed species, and finding ways to cultivate and market them to the masses. On Long Island, Purple, Red, White, Whorled, and Green Milkweed are all either threatened, endangered, or already extirpated within the state, as is the case with Red Milkweed, which was endemic to only LI within the New York and is considered rare throughout its greater range. These are the species that need to be preserved and cultivated for future generations, both within the wild and within our gardens as extensions of the nursery industry.
The same argument can be made for those who grow Culinary Herbs to support Eastern Swallowtails. While quick-growing annual herbs that can be also be utilized by caterpillars may seem like a simply and easy solution, it is not doing anything to preserve the habitat and the natural species that these insects evolved in partnership with for Millennia (the main issue facing wildlife). It stands to reason that by offering these exotic host species at greater numbers than their native counterparts we may actually be effecting the insects' preference for which species it considers a host, as has been observed by many gardeners who happen to be growing both culinary and native host plants.
The solution is simple, native species are always better suited for supporting our native wildlife, especially for the insects that have evolved for millions of years alongside their respective hosts. "Vote with your dollar", and only purchase native plants to your region, and ensure you support any local growing operations that do in fact cultivate our native Milkweed Species. Be wary of any marketing ploys that may push some agenda in order for you to purchase their product and always do your own research from reputable sources as well as purchase your plants from a reputable ecologically-focused nursery. Together, we can preserve our native Milkweeds before they are lost and ensure our wildlife persists for our grandchildren to enjoy just as we do today.
Native Milkweed (Asclepias) Species:
A. amplexicaulis - Blunt-Leaved Milkweed
A. amplexicaulis x A. syriaca = A. x intermedia - Intermediary Milkweed
A. exaltata - Poke Milkweed
A. incarnata spp. pulchra - Eastern Swamp Milkweed
A. pupurescens - Purple Milkweed
A. quardrifolia - Four-Leaved Milkweed
A. rubra - Red Milkweed *extirpated
A. syriaca - Common Milkweed
A. tuberosa - Butterfly Weed
A. variegata - White Milkweed
A. verticillata - Whorled Milkweed
A. viridiflora - Green Milkweed