Ask someone what scares them and plants probably aren’t the first things that come to mind. They likely don’t even crack the top 10.
A visit to the Ambler Campus Greenhouse, however, shows that the thriving foliage isn’t all pretty flowers and sun-dappled leaves. The Greenhouse — and in some cases the Ambler Arboretum — provides a perfect home for an eclectic group of carnivorous plants, spiny cacti of every shape and size and species that are a great deal more bizarre.
Take the Amorphophallus titanum, the largest "unbranched inflorescence” in the world. The tallest flowers grow to about seven feet in height while the leaves spread a full 12 feet and the tuber weighs in at a monster 150 pounds. Ambler Campus Greenhouse Horticulturist Ben Snyder is currently growing five of them and after a year and a half they are as tall or taller than he is.
“Our Amorphophallus have been grown from seed donated by Ohio State University. You have to be patient with these plants as it typically takes seven to 10 years for them to flower and, in some instances, it can take up to 15 years,” Snyder said. “When they bloom, it’s truly an event because it’s still quite rare in cultivation and the bloom only lasts a couple of days. You will have huge crowds come to see an Amorphophallus bloom.”
The fact that it attracts so much in-person interest runs counter to its other most well-known trait — when blooming it smells like death to an eye-watering degree. It’s not called a corpse flower for nothing!
“The stench, the speckled maroon and pink coloring, it is this flower’s way of attracting pollinators. Rather than bees and butterflies, it attracts anything that would naturally be attracted to rotting meat, such as beetles and flies.
According to Snyder, the Amorphophallus titanum also goes through "thermogenesis." It can generate its own heat to a level that nearly mimics human body temperature, just another way to fool its pollinators.
“It’s a technique that isn’t unique to the Amorphophallus. Our native skunk cabbage (Symplocarpus foetidus) blooms early; it can melt the snow around the flower,” he said. “And yes, as the name suggests, they also stink and rely on flies and beetles as pollinators.”
Not too far from the future monstrous blooms tropical pitcher plants hang innocently enough — unless of course you happen to be an insect. Instead of using them as pollinators, Pitcher Plants have an altogether different use for insects.
“Pitcher plants are meat eaters. While the tropical pitcher plants (Nepthenthes) are not native to Pennsylvania, we have used the hardier Sarracenia in some of our Flower Show exhibits,” said Snyder. “The majority of tropical pitcher plants are epiphytes; they do not grow in soil. Typically they attach themselves to tree branches so they aren’t deriving nutrients from soil — that’s what they get from the insects.”
According to Snyder, insects that fall victim to a pitcher plant are essentially succumbing to a slip-and-fall accident. The insect lands on the slippery nectar on the underside of the pitcher plants lids; one slip later and it’s down the hatch. While the pitcher plant lets insects come to it, the Venus flytrap takes a more active role in nabbing a meal.
“If an insect touches three hairs inside the ‘jaws,’ it triggers an electrical signal which tells the flytrap to rapidly move liquid into the cells to close around the insect. This is caused by rapid cell expansion; the plant rapidly fills itself up with water, blowing up the cells,” Snyder said. “This causes a great deal of stress on the plant — they’ll only eat three to four insects in their lifetime. So it may seem fun to let a flytrap close on your finger, but you’re actually placing tremendous stress on the plant.”
Snyder said while Venus flytraps may seem quite alien, or at least tropical, they are actually native to North Carolina.
“They are hardy, native and carnivorous, similar to Sarracenia and sundews. The sundew is active like a flytrap; they’ll entire a fly to its pad with nectar and curl up over itself,” he said. “These are all terrestrial plants that grow in low nutrient, low oxygen, acidic environments, like bogs. They still experience photosynthesis, but supplement that with meat. The slobbering pine uses the same method as the sundew but is native to the Mediterranean region where it prefers dry locations where there is low nutrient, sandy or gravely soil.”
Amid the other interesting oddities within the Ambler Campus Greenhouse is a rather unassuming vine, the Tetrastigma, a member of the grape family that in and of itself isn’t all that strange — until to add in the parasitic Rafflesia, the world’s largest single flower, which looks like it would feel right at home in the film Alien or Little Shop of Horrors.
“It has no stem, no leaves, no roots of its own. It only emerges from the Tetrastigma to flower,” Snyder said. “It’s red and fleshy and, yes, it stinks, and attracts beetles and flies as its pollinators. It is endangered and the location of flowering plants are often closely guarded, but maybe one day you’ll find one here in the Greenhouse!”
What you can find is hundreds of cacti and succulents, the variety of which almost boggles the mind.
“Spines are usually used for defense. Hairs, however, have multiple uses,” Snyder said. “Certain succulents use them for sun protection. There are species native to the Peruvian Andes that use the hairs to collect condensation from fog. Plants find truly amazing ways to adapt to their environments.”
Snyder said many of the more interesting species in the Greenhouse collection are used by classes — Plant Physiology for example — to get up close with plants that they might otherwise never experience.
“It’s an opportunity for our students and visitors to the Arboretum to see the incredible diversity of plants and their adaptations. You’re not going to run into something like the Amorphophallus very often, if ever,” he said. “It raises awareness of an interest in nature and the world around us. We have this wonderful collection of fascinating plants and the Greenhouse is open to students, faculty, staff, alumni and visitors — we hope more and more people take advantage of it.”