Tired of the same old Halloween decorations? Maybe you’re ready for Booo-tany! There are plenty of plants that embody spooky themes, and what could be cooler than dressing up as a corpse flower or parasitic dodder? (If you do, send photos….). Here we highlight just a few of the Booo-tanical wonders to inspire your festivities; more haunted herbals are listed below.
The undisputed top witch has to be Striga, known as witchweed because when a field is infected it appears as though it has had a spell cast on it. Striga spp. are parasitic plants that are particularly prevalent in nutrient-poor soils throughout Africa and parts of Asia where they weakens crops such as rice and corn (Scholes and Press, 2008). They and related plants in the genus Orobanche are estimated to cause 10 billion dollars in crop losses annually, a truly scary thought.
Witches’ broom refers to a growth habit of woody plants in which a broom-like cluster of branches forms. Several factors can lead to this growth response, including infections by bacteria or fungi or insect attack. Witches’ broom disease caused by the fungus Moniliophthora perniciosa is one of the most serious diseases of Theobroma cacao, the tree that gives us chocolate (Meinhardt et al., 2008). What would Halloween be without chocolate?
Finally, although not plants, the ergot fungi produce ergotamine alkaoids that have been suggested as a contributor to witch folklore and more (Caporael, 1976).
Werewolves are said to be humans who change into hairy wolves during a full moon, so we have two good candidates for plant werewolves. The first is an Arabidopsis mutant called werewolf, which makes too many hairs on its roots (Lee and Schiefelbein, 1999). OK, maybe not the stuff of nightmares, but it provided insights into the developmental program of root hair development, and that’s pretty important for understanding nutrient uptake etc.
The other candidate doesn’t look like a werewolf but it behaves like one. Ephedra foeminea is an insect-pollinated gymnosperm that produces pollen drops to coincide with the full moon (Rydin and Bolinder, 2015). Some insects forage more in the bright light of the full moon, and it’s thought the moon’s reflections in the pollen drops attract insects to the male cones. It’s something pleasant to think about next time you’re walking in the dark woods under a full moon.
They’re not werewolves, but flesh-eating (carnivorous or insectivorous) plants are pretty creepy too – check out Chris Martine’s Plants are Cool, Too! Halloween Special, or this sundew video featuring David Attenborough.
Vampires and bats
Vampires are known for feeding off the blood of their victims. Just about any parasitic plant fits that description, but we have selected parasitic dodder as our top vampire plant, even if for no other reason than the fact that David Attenborough calls it a vampire plant too.
Dodder (and other parasitic plants) produce structures called haustoria that penetrate their host and provide conduits for nutrients to flow into the parasite. Some like Striga are root parasites, and others like dodder and mistletoe are shoot parasites. Dodder is particularly eerie in the way it is able to sense its host, by “sniffing” the volatile compounds it produces. If you’re in the US you can see more about how dodder senses its prey here (not available outside US). More dodder photos can be found on Phil Gates’ website A Digital Botanic Garden.
In some stories, vampires can transition into bat form, possibly looking something like the black bat flower (Tacca chantrieri). Interestingly, this bat-like flower does not appear to be bat pollinated (Zhang et al., 2005), although bats are important pollinators. The blog Tropical Biodiversity has an excellent post on this plant here. (Remember, bats are benign and need our support; to learn more check out Bat Conservation Trust, Bat Conservation International, and Bat World Sanctuary).
Ghosts and corpses
Ghosts are body-less yet visible spirits, and are often described as white or colorless. Ghost flowers (Monotropa uniflora) are another type of parasitic plant, which are so described because they lack pigmentation and are white (see more at the Botanical Society of America and USDA websites). Without the ability to photosynthesize, they are obligate parasites, but curiously their hosts are fungi.
If ghosts are spirits without bodies, we might consider corpses to be their complements. Several plants give off the smell of rotting flesh to attract pollinators. The enormous stinky corpse flower (Amorphophallus titanum) is the star of many botanic gardens; here it is being explored and sniffed in the wild by David Attenborough. Other contenders for the title of top corpse plant including the dead horse arum (Helicodiceros muscivorus, fantastically described here by David Attenborough) and voodoo lily (Sauromatum venosum). You can explore more stinky and creepy plants at RottenBotany, the website of Amber Guetebier.
And if you haven’t had enough of all this morbid booo-tany, why not check out Morticulture: Forests of the living dead.
The modern symbol of Halloween is the pumpkin, but if you want to be true to Halloween’s roots, why not carve a turnip this year? (Depending on where you live, you might call a turnip a neep, or a swede, or a rutabaga – we’re talking about the big yellow Brassica napus, not the small white Brassica rapa rapa). European immigrants brought their tradition of carving Jack-o-Lanterns from turnips to the New World but replaced the turnip with the more abundant and easier-to-carve pumpkins. If you have a few hours this weekend, try carving a turnip. Being solid rather than hollow, they are much harder to carve out, but the smell of a Halloween candle burning inside your Jack-o-Lantern turnip is indescribably eerie and a unique addition to your Booo-tanical festivities.
ADDENDUM: After posting this several additional plants were suggested by readers. Here are a few additional candidates:
Bleeding heart (Lamprocapnos spectabilis) and wolf’s bane (Aconitum)?
— Benjamin Edge (@edgeben) October 31, 2015
Here’s a nice graphic, contributed by Lynn Sosnoskie:
Bawden, T. (2015). Scientists discover world’s first-known “werewolf plant”. Independent. 1 April 2015.
Caporael, L.R. (1976). Ergotism: the satan loosed in Salem? Science 192: 21–26.
Earthrangers (2011). Top Ten Spooky Plants.
Hertz, K. (2015). Original Irish Jack-o-Lanterns were truly terrifying and made of turnips. Irish Central.
Lee, M.M. and Schiefelbein, J. (1999). WEREWOLF, a MYB-related protein in Arabidopsis, is a position-dependent regulator of epidermal cell patterning. Cell. 99: 473-483.
McIndoe, A. (2015). Witches, weeds and ghostly plants for Halloween. My Garden School, 30 Oct. 2015.
Meinhardt, L.W., Rincones, J., Bailey, B.A., Aime, M.C., Griffith, G.W., Zhang, D. and Pereira, G.A.G. (2008). Moniliophthora perniciosa, the causal agent of witches’ broom disease of cacao: what’s new from this old foe? Mol. Plant Pathol. 9: 577-588.
Rich, P.J., and Ejeta, G. (2008). Towards effective resistance to S. hermonthica in African maize. Plant Signal Behav. 3: 618–621.
Rydin, C. and Bolinder, K. (2015). Moonlight pollination in the gymnosperm Ephedra (Gnetales). Biology Letters. 11: 20140993.
Runyon, J.B., M.C. Mescher, and Moraes, C.M. (2006). Volatile chemical cues guide host location and host selection by parasitic plants. Science 313: 1964-1967.
Scholes, J.D. and Press, M.C. (2008). Striga infestation of cereal crops – an unsolved problem in resource limited agriculture. Curr. Opin. Plant Biol. 11: 180-186.
The Telegraph (2013). Halloween: The world’s spookiest plants.
Zhang, L., Barrett, S.C.H., Gao, J.-Y., Chen, J., Cole, W.W., Liu, Y., Bai, Z.-L. and Li, Q.-J. (2005). Predicting mating patterns from pollination syndromes: the case of “sapromyiophily” in Tacca chantrieri (Taccaceae). Am. J. Bot. 92: 517-524.
Werewolf plant: Gideon Pisanty
Black bat flower: Meneerke bloem
Dodder section: Spike Walker, Wellcome Images B00004464
Ghost plant: Indian Pipe PDB