With the ever-evolving symphony of fall color mingled with the season finale of flowers and the subtle beauty of the seeds, November knows how to bring the season to a magical close! Seeds are an understated part of the show and perhaps no plant has elevated the beauty and art of seed dispersal better than Milkweed. Botanically known as Asclepias, the parachute-like seed structures shimmer in the low November sun before gracefully setting sail and floating about the garden. The seed pod and seeds of Asclepias syriaca are pictured below on a frosty late December morning. The genus also features attractive floral displays during the warmth of summer while serving as an important lifeline for the Monarch Butterfly.

Asclepias has roughly 200 species found in North and South America along with parts of Africa. Originally, it was in its own family of Asclepiadaceae but has since been shifted to the Dogbane Family or Apocynaceae. The genus name was officially penned in 1753 by the Swedish botanist Carl Linnaeus (1707-1778) in honor of Asclepias, the Greek god of healing and medicine. To this day his snake wrapped staff remains the symbol of modern medicine! The inspiration for honoring the deity is somewhat clouded, although one possibility centers on the Swedish botanist Caspir Bauhin (1560-1624). Although Bauhin focused heavily on the study of human anatomy, he is best known for his work in botany and the concept of classifying plants by genus and species, a concept Linnaeus later championed. In 1623 Bauhin published a book on herbals entitled Pinax Theatri botanici (Illustrated Exposition of Plants), describing over 5,600 plants. Within this treatise he mentions an ancient herbal named Asclepius used by the Roman naturalist Pliny the Elder (23/24-79 AD) and the Greek pharmacologist Pedanius Dioscorides (40-90 AD). The herb was said to be effective against poisoning. Bauhin also mentioned how the plant was recently discovered across the Atlantic in the region known as Virginia. Recognizing that Milkweed was used as an herbal by Native Americans and was possibly the recently discovered plant of Virginia that Bauhin mentions, Linnaeus may have been suitably inspired to adopt this name as the genus for Milkweed.

Asclepias benefits more than simply humans, since many insects are also reliant on the genus including the afore mentioned Monarch Butterfly. In fact, interest in planting Asclepias has grown rapidly over the past 20 years when it became apparent the dwindling population of Monarch Butterflies was directly tied to dwindling populations of specific Milkweed species. Oddly, this relationship originally developed because the sap and tissues of Milkweeds are poisonous to eat due to the presence of toxic steroids called cardenolides. These compounds arenaturally occurring cardiac glycosides that impact the heart and evolved within the plant to prevent predation. Much to the plant’s consternation I’m sure, Monarch butterflies underwent several genetic mutations providing immunity to these steroids. The concentration of these steroids within the caterpillar and later the butterfly gives them a bitter taste, rendering them unpalatable to birds. The bright orange color of the adults and bright yellow, black and white markings of the caterpillar evolved as visual clues to birds that these insects are not a tasty snack – a phenomenon called aposematic coloration! Unfortunately, these genetic mutations took the caterpillar’s dietary intake one step further and restricted its food palate to only Milkweed. Specifically, Monarch caterpillars can only survive on 27 of the 115 North America Asclepias species. Attempting to eat another plant would result in death. The old adage of ‘Best Laid Plans’ is proving true again as the massive amount of agricultural spraying combined with urban sprawl has resulted in reduced habitats for Asclepias, resulting in declining Monarch populations.

Fortunately, the plants add wonderful beauty to the garden and the educated gardener can help resolve the Monarch’s plight by simply planting Milkweed! Depending upon the garden’s style and growing conditions, there are several readily available species from which the gardener can select. Perhaps the most well-known selection is Asclepias tuberosa, simply known as Milkweed. Despite its common name, it does not display the milky white sap that fostered the common name for the genus! Named by Linnaeus in 1753, the plant is native from Quebec west to South Dakota and South to Florida and Southern California. As the species name suggests, it grows from a tuber and is a clump forming perennial. Growing to 12-30” tall, plants prefer a sun-drenched location that is typical of the genus in general. This species also prefers average to dry soils. The slender lanceolate foliage reaches lengths of 3’’ and is arranged alternately along the hairy stems. The ⅜” diameter flowers are orange, reddish orange or more rarely yellow and appear on umbels ranging from 2-5” in diameter. By definition, an umbel is a flower cluster in which the floral stems or peduncles are all of approximately equal length and originate from the same point (as pictured above). With upwards of 20 flowers per umbel, the plants provide impactful color from June through September. Plants self-sow generously and are short-lived, relying on the seedlings to maintain and perpetuate healthy populations. Plants are hardy in zones 3-9.

If the soil conditions are moister, consider Asclepias incarnata or Swamp Milkweed. It is native to every state except those states bordering the Pacific and Mississippi. In Canada it is also found from Quebec west to Manitoba. This plant was once again named by Linnaeus in 1753, with the species epithet derived from the Latin Carn or Carnis meaning meat or flesh and Ātus meaning like or possessing a feature, describing how the flowers have a fleshy pink color (as seen above). Also hardy in zones 3-9 and a clump former, it grows much taller than its cousin, easily reaching 3-4’ tall. The foliage is also lanceolate, reaching upwards of 1” wide by 4-6” long and arranged oppositely along the mostly hairless stems. The individual flowers are a bit smaller, measuring around ¼” in diameter but, with each inflorescence consisting of several umbels, the overall impact is more dramatic! Belying its common name, it readily grows in soils of average moisture although soils should not dry out during the spring flush.

Another readily available species is Asclepias syriaca or Common Milkweed. It too has large umbels of pink flowers but unlike the previous two species, it has a deep and broad spreading rhizomatous root system. Its tendency for stems to magically appear far from where it was initially planted makes it an ideal candidate for more naturalistic designs than a structured garden. Once again named by Linnaeus in 1753, the species name means ‘of Syria’ based on the mistaken belief of the plant’s origin. Native from the regions of New Brunswick and Quebec west to Saskatchewan and south to Texas and Georgia, it is also found in Oregon! Once again hardy in zones 3-9, it typically grows to 3-4’ tall and has much coarser foliage than the previous two species, measuring 6-8” long by 2-3½” wide (as seen above). There is certainly no denying its importance to the world of insects. With over 450 insects known to dine on this plant, it serves as the mega diner for those ‘little things that run the world’ as the entomologist E. O. Wilson (1929-2021) once wrote! The individual flowers are once again smaller, measuring ¼” in diameter, but with upwards of 100 flowers per umbel, the show remains spectacular. When all the flowers of an umbel are in bloom, the overall weight of the flowers causes the ball-like umbel to hang downward, although the impact is still effective.

In addition to displaying beautiful flowers and assisting in the life cycle of the Monarch Butterfly, all these species bring curious horn-like seed pods and the motion of floating seeds to the November Garden. The curious part of these pods is the sheer number of seeds held in each pod – all produced from such seemingly small flowers. The answer to the abundant seed set lies in the colorful and magically complex flowers that certainly deserves a closer look!

Unlike most flowers, the petals do not serve as the primary lure for attracting pollinators. Rather, they reflex downward and remain mostly out of view from the visiting pollinators. Also unique to Asclepias is how the male anthers and the pollen receptive female stigma, along with their supporting structures (the filament and style respectively) have become fused into a central column called a gynostegium. This structure has a relatively small, flat top that is white or light yellow in color (as seen at the tip of the arrow above). Surrounding the gynostegium and serving both as the lure for pollinators and giving the flower its overall shape is the corona. The corona or ‘crown’ takes the form of five cup-like vessels and develops from the base of the male stamens. These five vessels are called Hoods and, their function aligns with their cup-like shape, as they hold copious amounts of nectar to lure in pollinators. The glistening nectar can be seen in several of the hoods above. Adding to the complexity of the corona are five tapered structures called Horns with each Horn emerging from the center of a Hood. The Horns curve into the center of the flower, with the pointed tip hovering over the center of the gynostegium (again seen above). The function of these mysterious looking Horns is to create unstable footing for the pollinator.

Another mystery of this flower is the visual absence of pollen. Since the anthers are partially responsible for creating the gynostegium, the answer to this mystery lies within the central column! It contains 5 cavities called stigmatic chambers with each chamber containing a pollen receptive stigmatic surface, a nectary that fills the cup-like Hoods with a sugary fluid and two pollen containing pollinia. Unlike most flowers that have individual grains of pollen, species of Asclepias encase the pollen within a waxy sac, allowing the insect to move many grains of pollen at once. This trait is also seen in Orchids. Each of the 5 chambers can be accessed by a slit in the side of the gynostegium called the stigmatic slit (seen at the tip of the green arrow above). Located just above this slit is a small black structure called the corpusculum which is connected to the 2 pollinia within the chamber by 2 arms, sensibly called the connective arms! All of these organs combined – the corpusculum, 2 pollinia and 2 connective arms – create a saddlebag-like structure called the pollinarium. The corpusculum (seen at the tip of the blue arrow) and the stigmatic slit beneath can be seen in the image above.

When a pollinator lands on a flower to partake of the nectar, the Horns cause the insect to stumble about and invariably a leg may pass through a stigmatic slit. As the insect works to pull its leg from the slit, the leg becomes stuck in a narrow groove in the corpusculum. As a result, it not only pulls out its leg, but also the entire pollinarium. Of course, this requires a degree of effort and strength not every insect possesses. Older insects may not be able to remove their leg and will ultimately perish on the flower. Fortunately, most of the insects escape with the 2 pollinia in tow. Magically, 1½-2 minutes after the insect removes the pollinarium from the moist atmosphere of the chamber, the connective arms proceed to turn 90 degrees from their original orientation as they dry. This allows for the two pollinia to properly align with and pass through the stigmatic slit of a subsequently visited flower and come in contact with the stigmatic surface, resulting in pollination. Ingenious! Once the pollinia are safely in the receiving chamber, the connective arms break off while the corpusculum often remains on the insect’s leg for some length of time. Although ingenious, the process is certainly not failsafe. Sometimes the pollinarium dislodges in flight. Or, since the plants are self-incompatible, if it ends up in the chamber of another flower of the same plant, pollination will not occur. Or, the insects’ leg may simply fail to enter the chamber!

Assuming pollination occurs, the ovaries develop into horn-like follicles or seed pods, measuring upwards of 3-5(6)” in length. The mature size of the pods is ultimately dependent upon the species, with the developing pods of Asclepias tuberosa pictured above in September. It is not uncommon to only see one or two pods developing from the numerous umbels and several hundred flowers present on a given plant. When they ripen in late October and November, they split open along a seam running the length of the follicle to reveal 200-400 brown seeds neatly arranged in rows. The large number of seeds are the result of the many grains of pollen contained in the pollinia! Attached to the seed is a feathery plume called a coma, which resembles the pappus attached to Dandelion seeds. Pictured above are the coma tipped seeds of Asclepias tuberosa in mid-October. Although the function of moving the seed about by wind is identical, they are different in origin. A coma develops from the seed, while the pappus develops from the sepals of the calyx. For Asclepias, each 1-2” long coma is attached to the narrower end of the ovoid shaped seed and is composed of cellulose. Although it appears solid, it is actually a hollow tube, allowing it to magically float about in the air or on the surface of a stream as it travels to its new home. In fact, during WW2 the buoyant comas were gathered to fill life preservers for the military!

Asclepias plants combine well with shorter or more upright forms of ornamental grasses such as Schizachyrium scoparium (Little Bluestem) and various Carex species or with blue flowers as seen below at Chanticleer. For those species preferring drier conditions consider combining them with selections of Rudbeckia (Black-eyed Susans), Penstemon (Beardtongue) or Campanula (Bellflower). Swamp Milkweed looks great with moisture loving Iris, Iron Weed (Vernonia), Sedges including Carex stricta and even some of the shrubby Willows (Salix spp.). All three species are readily available at garden centers and for the deer wary gardener, the bitter taste from the cardenolides also provides good browse resistance.

For gardeners who enjoy the magical motion of those fluffy comas or butterflies flitting from flower to flower, these species of Asclepias are garden essentials. For children and those young at heart, the thrill comes from collecting and rubbing the incredibly smooth comas between your fingers or blowing the seeds from your palm. Without doubt, plants like Asclepias help to make November a most magical month!

By Bruce Crawford, Manager of Horticulture, Morris County Parks Commission