Scary decorations and costumes can be purchased for a creepy Halloween. However, nature provides some truly ghoulish plants that are guaranteed to cause a frightful experience. Some of these frightful plants have terrifying names, while others are poisonous, emit a rotting flesh odor, or are just plain scary in appearance. Beware! These plants may haunt your dreams.
Brain cactus 'Cristata' (Mammillaria elongata) is a plant that resembles the twisted lobes of the human brain with hairy spines (Figure 1). It grows to six inches tall when planted in a container with a well-drained cactus potting mix. It thrives in a warm room with full sun and requires little water, especially during the winter months. When watering, direct the spout to the soil to prevent moisture from collecting on the plant, which may cause rot. Although the brain cactus develops flowers, it's more often grown for its creepy appearance. A spotlight on a brain cactus potted in a skull in a dark room will surely spook any Halloween evening party guest.
Blood root (Sanguinaria canadensis) is a native wildflower found in shady woodlands and along streams in many counties in Missouri. During March and April, this plant produces white-petaled flowers with yellow centers. However, its fleshy underground stems and roots exude reddish-colored fluid that creates a macabre scene when cut (Figure 2). Beware of skin contact with this sap, since it can cause a rash. Bloodroot is also poisonous when ingested in large amounts.
Devil's claw (Proboscidea louisianica) will grab anyone's attention as the seed pod snatches onto the clothing of a passerby. When dry, the reflexed appendages of the fruit capsules become terrifying and often become entangled in the fur of animals (Figure 3). Cattle can starve when the claw-like pods become attached to their mouthparts. During flowering, the tubular, yellowish flowers arranged on a spikelike raceme emit a foul odor. During pollination, the flowers are sensitive to touch, snapping shut when an insect or fingertip contacts the petals. This wild plant is found in open, disturbed areas, mostly along the Missouri River and in southern counties of the state.
Poison hemlock (Conium maculatum) is a biennial plant, containing poisonous alkaloid compounds in the stems, fern-like leaves, clusters of white flowers, and seeds. During the first year's growth, the leaves are low-growing, forming a rosette. In the second year, stems elongate, and flowers and seeds develop (Figure 4). It grows up to 10 feet tall in moist soil along roadsides, pastures, and wasteland. Poison hemlock leaves and flowers resemble those of wild carrot, also known as Queen Anne's lace (Daucus carota). However, wild carrot plants only grow to about two feet tall. Poisonous hemlock is best left growing in the wild as it is highly toxic to humans and pets. This notorious plant is forever linked with Socrates, as he perished after drinking a potent concoction of poisonous hemlock in 399 BC.
True to its name, the large, star-shaped flowers of the carrion plant (Stapelia gigantea) produce a frightful odor that will send Halloween trick-or-treaters running (Figure 5). Although repugnant to humans, the odor, which is reminiscent of rotting flesh, attracts flies for pollination of flowers. Carrion plants are spineless succulents native to desert regions that grow to one foot tall. For those with a morbid sense of smell, flowering plants can be experienced at the Missouri Botanical Garden and other public greenhouses.
Another plant with a malodorous flower is the titan arum or corpse flower (Amorphophallus titanium). However, this giant plant requires about five to ten years to produce a spectacular flower that reaches up to eight feet tall. For plant enthusiasts, the unfurling of a huge leaf, exposing the eye-popping flower is a highly anticipated event at botanical gardens (Figure 6). At peak bloom, the flower reeks of a strong, putrid odor for about six to twelve hours.
The black bat or devil plant (Tacca chantrieri), which is indigenous to rainforests produces malevolent-looking flowers that are up to twelve inches wide. The dark-purple flowers are surrounded by wing-like bracts with long eight- to ten-inch-long whiskers at the base of the inflorescence (Figure 7). Botanically, the whiskers are bracteoles. The motion of bracteoles may attract mammal-biting Forcipomyia midges, although the actual function of these structures on black bat plants is unknown.
The spooky ghost plant (Monotropa uniflora), which is also known as Indian pipe, is found growing in clusters in many Missouri counties. However, it may take a team of ghost-busters to locate this plant, which is typically under one foot tall. Hunt for these wraithlike plants in the leaf litter of trees in damp, dark woods. The eerie white stems of this plant lack chlorophyll and are unable to produce the green pigment by photosynthesis (Figure 8). Instead, the roots of ghost plants obtain their nutrients for growth via mycorrhizal fungi. A drooping solitary flower can be found at the end of each stem in August through October. Please leave these ghostly plants in the wild. Nightmares of their demise may long haunt you after unsuccessfully trying to transplant them elsewhere!