Milkweed Classification

Milkweed classification is the way in which different milkweeds are put into groups with other similar milkweeds. Milkweed classification is not that difficult to understand but can be because of how many different types there are. There are also always new milkweeds being discovered. Overall, there are about 120 different kinds of milkweed(“Milkweed”). Milkweed classification is important to understand to save monarchs from going extinct.

The scientific name for milkweed is Asclepias (the genus), which is part of the family Asclepiadoideae.

Asclepiadoideae is part of a larger family called Apocynaceae. Milkweed is considered a perennial herb. North America has many different types of milkweed spread across it. The most common milkweeds known to North America are the common, butterfly, and swamp milkweeds, which are not poisonous, and narrow-leaved labriform, narrow-leaved whorled, and broad-leaved woolly pod, which are highly poisonous.

Labriform leaves look as though they have a lip and whorled leaves spiral. Broad leaves are simply wide. Common milkweed is the most populous in North America, mainly in the eastern part of the United States, spreading as far south as Georgia. There are many more types in North America, but most milkweed plants are found in South America. This is because many people believe that milkweed originated in South America during the Pangaea Era (Karges 36). The milkweed spread to the other continents and flourished, creating many of the types we have today and even still creating new types. Some milkweed plants are inaccessible by humans, so only a few botanists really know about them. This could mean that there are milkweed plants that we do not even know about.

Milkweed leaves are the only food for a monarch caterpillar (“On the Wings of a Monarch”), however, people are abusing the growth of milkweed plants because they believe it is just a garden pest, but it is really hurting the monarchs (Benson 31). The monarch population is decreasing for this reason and many others, too.

Each milkweed plant has a slightly different anatomy than the next, but there are very basic things that remain the same, or at least very similar. The shapes are either flat, bell-shaped, or something like a tube. All milkweeds have five sepals, five stamen, five corona, and five corollas. Sepals surround the flower’s petals. Stamen are the male reproduction parts of a flower. The coronas are cupped outgrowth that come out from the center of the flower. Finally, the corollas are simply the petals of a flower.

The corolla lobes are attached to the gynostegium, or the center ring, which is where the reproductive parts of the plant are located. The stamen and pistils (female organs of a flower) come together to form something like a column. They extend above the ovary where the pollinia (sacks of pollen) are located and can be extracted. This is also where the new seeds are created as well. However, the structure will vary from one plant to the next. For example, the anthers (pollen part of the stamen) could bend over the central column of the milkweed, but some can be flat.

Milkweed also have flowers that grow with it. These flowers can be found in clusters, such as cymes (has a central stem), umbels (many short flower stems), or racemes (separate flowers connected by short stems). Their color can be anywhere from white to yellow and red to purple. There are different designs that can be on the flowers, too. These designs can be simple streaks, dots, or wavy lines. No matter what the flower looks like or what milkweed it is a part of, they will all be organized into groups of two to five whorls. The flowers form in clusters at the top of the plant or along the plant’s stem. Most flowers can be identified by their “five over five”. Five droopy and five upright petals can be found on each flower, and each have hoods. Each hood has a “horn” that curves slightly inward.

The location of where a milkweed plant can be found is pretty much unlimited. It can be found in rainforests, deserts, marshes, sandy hills, and plains. Wherever these plants are found, they will most likely have straight stems and whorled leaves, however, some plants can have very tiny leaves, and some might not even have any. Some milkweed plants have been found in vines that have prickly stems. Others look like bushes or even a small tree. One fun fact about milkweed is that it can reproduce in its roots underground (Baskin).

The number of milkweed plants out there is large. These are just a few examples and their locations: swamp, butterfly, antelope horns, showy, rush, Indian/woolly pod, and tropical. Swamp milkweed is always found around or in water. Butterfly milkweed is found in the Midwest and upper south. Antelope horns is found in Texas and Arizona on pastures and hillsides. Showy milkweed is found in or north of Colorado and New Mexico.

Rush milkweed can be found in California in its deserts and canyons. Indian (or woolly pod) milkweed can also be found in California, but in its fields. Finally, tropical milkweed is found almost everywhere. The locations of these milkweeds can impact your decision when trying to decide what type of milkweed the plant is or what category it fits under, but this can’t be the only thing that is used to determine this.

All milkweed is divided into two groups. One is broad leaved, and the other is narrow leaved. From these categories, the milkweed is then characterized by their sap (latex) and by inflated fruit pods that contain a cotton-like fuzz. This fuzz is essential to the survival of all milkweed plants. This is because once a pod has matured, it releases this fuzz. Each fuzz has a seed on the end of it. The fuzz and seed are light enough to be carried by the wind over any varying distance. This allows for the spreading and reproduction of the milkweed plant that the seed came from.

One of the milkweeds everyone should understand is the common milkweed. Common milkweed can be found along roads, fields, and even in waste places. The stems can be anywhere from 3 ?? feet to 6 ?? feet long. It has hairy green leaves on short stems and has flowers. The flowers are located toward the top of the tip of the stem. Common milkweed also has a lot of pollen. Whenever insects walk on it for its nectar, it must walk all over the pollen. Then, when the insect leaves to go to another plant, it cross pollinates with other milkweeds.

Another milkweed that is important to know is the butterfly milkweed. It needs very little care to survive because it can keep away insect predators and deer and can even keep away disease. Butterfly milkweed can easily grow in dry soil. The height that this plant normally grows to is 2 ?? to 3 feet tall. The leaves are green and grow 2 to 5 inches long that twist up the fuzzy stem. The flowers grow 3 to 6 inches long and once this happens, the green pods form, split, and let out the fuzz. Another important fact is that butterfly milkweed does not carry the toxic sap that other milkweed plants do.

Milkweed may be good for a monarch’s survival, but the increased temperature change around the world is affecting them negatively. The high temperature results in a high amount of cardenolide which is a toxic steroidal compound that can be found in milkweeds. The monarchs have been studied and it is shown that this change can kill monarchs (Moore 8). Milkweed has been hurting other animals, too. Organisms that consume and cannot handle the cardenolide experience muscle spasms, symptoms of depression, and weakness (Today’s Science Encyclopedia).

There are not only bad things that the milkweed plants are doing though. Many butterflies, excluding monarchs, have started eating milkweed. They are also using it for its nectar and pollen. Other butterflies are not even the only other organisms adapting to eating milkweed. Moths, grasshoppers, and other small bugs are eating milkweed for survival, too.

Being able to understand the classification of milkweed is very important for everyone. It is key when trying to understand monarchs and how they live on a day-to-day basis. Low milkweed levels are resulting in a decreasing population of monarchs (“Monarchs Need Milkweed”). If we do not understand the importance of milkweed to a monarch’s survival, monarchs may go extinct just because the nation never bothered to learn about it.

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