We admire flowers for the beauty and alluring scents they bring to our personal and public landscapes. Flowers are a matter of pride for gardeners, a means of expression for lovers and they play a role in some of our most joyous and somber societal rituals. With almost $4 billion in sales in 2006, floriculture is also an economically important industry in the United States [source: Economic Research Service].
But to the plant, flowers are a deadly serious business. The plant's survival depends on the appeal of its flower to a distinctly non-human client list. Sensory stimulating petals and odors have one purpose: to draw pollinating insects and animals to the plant's reproductive organs, the stamens and pistil, housed inside the flower.
Flowering plants are seed-producing members of the plant kingdom. Not all seed-producing plants flower, though. Gymnosperms reproduce through seeds housed in cones. These conifers show up in fossils dating back 360 million years. Angiosperms, the flowering plants, popped without precursors into the fossil record during the middle of the Cretaceous Period, about 130 million years ago [source: Kanapaux].
During that 130 million years, flowers took on an amazing variety of shapes, colors and scents in their efforts to attract the creatures they need to complete pollination and produce seeds for the next generation. Bees, bats, birds, butterflies and other pollinators respond to different stimuli. Successful plants developed flowers that deliver the particular stimuli required to interest their pollinating partners, as well as hospitable physical traits, such as landing platforms for insects. The orchid family, Orchidacaea, is the largest and most diverse family of flowering plants. There are least 28,000 species and more than 300,000 cultivars of orchids, with more developing almost daily [source: Thomas]. One species, the bee orchid (Ophrys apifera) of the British Isles, mimics a female bee in appearance and scent to attract the earlier hatching male bees that spread its pollen around.
There are currently 235,000 known species of flowers in the world, and more are discovered every year [source: Wahlert]. More than 60 percent of these grow in the warm, wet climate of tropical rainforests source: Marent]. Some tropical flowers go to extremes in size, odor and survival strategies. Most of these couldn't survive in a suburban garden, and you probably wouldn't want them to. Appeal to human sensibilities isn't foremost in their reproductive struggle, and who wants to be known as the neighbor who cultivated the stinkiest flower in the world, or "Audrey III"?
There are, however, some uncommon flowers that you can safely harbor in your garden or on your window sill. In this article, we'll examine 10 very unusual flowers, from bizarre tropical blooms that mimic carrion to native North American flesh eaters. We'll also look at some unique flowers that could add interest and conversation starters to your landscape.
Meet the world's largest flower on the next page.
The largest flower in the world, Rafflesia arnoldii, is actually a parasite. It relies completely on its host, the Tetrastigma vine, to provide it with roots, leaves, stem and chlorophyll. The corpse lily, as it's commonly known, expends all of its energy working through the vine to produce a 3-foot (1-meter) diameter bloom and thousands of seeds.
In the early 1800s, the British governor of Sumatra (then known as Bencoolen) was very interested in the diversity of life on the island. Sir Thomas Stamford Raffles made many expeditions into the jungle and discovered, collected and documented numerous previously unknown plants and animals. His friend, Dr. Joseph Arnold, accompanied him on one exploration in 1818, and together they discovered an enormous red flower with white spots and a disgusting odor.
The colonial explorers were lucky to happen upon the flower when they did. The bloom only lasts for three or four days. After that, it collapses into what rainforest photographer Thomas Marent describes as a "slimy black mass" [source: Marent]. Despite the fact that Raffles went on to establish Singapore and the Zoological Society of London, he is best remembered for his discovery of the corpse lily.
Native to the Indonesian islands Sumatra and Java as well as eastern Malaysia, the hefty flower starts out as a cabbage-like bud on the root of the host vine and takes about nine months to mature and open. A single flower can weigh up to up to 25 pounds (11 kilograms) and hold several gallons (liters) of nectar in a central cavern surrounded by five petals [source: Souza, Earlham]. It relies on carrion-eating flies and beetles for pollination, so the aroma it gives off is similar to that of dead, rotting animals.
The bizarre corpse lily is considered threatened or endangered in all of its habitats, but it seems to be its own worst enemy. The flowers are single sex and must be cross-pollinated to produce seeds, but female flowers are rare and don't often bloom in the same area or at the same time as the male flowers. If pollination is successful, the flower leaves behind a 6-inch (15 centimeter) round fruit that appeals to squirrels and tree shrews. They eat the fruit and scatter the thousands of hard, tiny seeds contained within it.
If you get a chance to see the flower on the next page, you'll want to skip the part about stopping to smell the roses.
As bad as the corpse lily smells, the Titan Arum is even worse. It's earned the title "worst smelling flower in the world." In its native Sumatra, it's called "bunga bangkai" or "corpse flower" because of the odor of rotting flesh that it emits. Like Rafflesia arnoldii, the Titan Arum relies on flies and beetles to pollinate it. But that's where the similarities end.
Where the corpse lily creates a giant flower without supporting structure, Titan Arum creates a giant structure that conceals thousands of flowers. The plant grows from a large tuber that can weight from 55 to 110 pounds (25 to 50 kilograms). The flowers emerge when the tuber is dormant. The plant then produces a large, petal-like leaf, the spathe, which forms a vase. The outside of the spathe is green; the inside is the color of red meat. From the center of the vase, a tapered column-like stem (spadix) grows straight up, reaching heights of 6 feet (2 meters) or more with a 3-foot (1-meter) diameter [source: University of Connecticut].
The base of the spadix supports thousands of smelly inflorescences hidden inside the spathe. Rows and rows of yellow male flowers grow above rows and rows of red female flowers. The spathe begins to open at night, leading researchers to believe that it relies on nocturnal flies and beetles for pollination. The smell is strongest for the first twelve hours it's open. The spadix gives off heat, possibly to further imitate a dead and decaying animal. The metabolic heat may also serve to spread the stench farther afield to lure in pollinators.
Although it's not noted for smelling like a corpse, the flower on the next page is known as the flower of the dead.
Flor de Muerto, a common Mexican perennial, is the closest thing nature has to a truly black flower. And "the flower of the dead" actually looks like it's dead. The tubular flowers hang downward from 6-foot [2-meter] stems in a seemingly wilted, withered state. The plant has black petals, black leaves, black fruit, black seeds and black pollen.
Though unusual, the black flower is far from rare. It's easily found growing on roadside embankments and pine or oak forests in the states of Hidalgo, Veracruz, Oaxaca and Chiapas as well as in Guatemala. In a 2003 study, Kenneth R. Markham and associates determined the combination of pigments and light absorption that allows Lisianthius nigrescens to achieve its black color. It's the only flower known to completely absorb all wavebands of both ultraviolet (UV) and visible light [source: Markham].
But the real mystery of the flower of the dead is how it survives in such profusion without the discernable aid of a pollinating animal. The second part of the Markham, et al. study was to determine what the "ecological consequences" of a black flower are.
The flower's form suggests that hummingbirds, moths or long-tongued bees would pollinate it. But the scentless black flower doesn't possess any attributes to attract these animals.
Color perception depends on pigments, light and, literally, the eye of the beholder. Humans, birds and insects see the colors of flowers differently. Bees have UV, blue and green color receptors. They're attracted to yellow and blue flowers, particularly those that reflect UV light. Researchers speculate that bees avoid the red flowers that attract hummingbirds because the flowers don't reflect UV light and bees don't process red. To a bee, these flowers would appear black. Moths, who do their pollinating work at night, seek out light colored, highly scented flowers. So how does L. nigrescens attract the type of animal that could pollinate it?
The researchers conclude that, "The problem of how this flower might attract the pollinators when it totally absorbs in both the UV and the visible [light] remains to be explained."
See the opposite of the world's blackest flower on the next page.
A dismal gray cactus sprawls across the sand. It sprouts a few ribbed, twiggy stems with fragile spines. It looks dead. And yet, sometime in June or July, this ugly waste will transform into the "Queen of the Night." Because in midsummer, a miraculous awakening takes place in the Sonora and Chihuahua deserts of Arizona, Texas and northern Mexico: the night-blooming Cereus cactus opens its white flower and perfumes the dry air.
More specifically, three species of night-blooming cacti, Cereus greggii, Hylocereus undatus, and Selenicereus, become queen for one night. As the sun goes down, the cactus opens 8-inch long by 4-inch wide (20-centimeter by 10-centimeter), many-petalled white flowers with yellow-tipped stamens [source : Royo, Ladyman]. The fragrance can spread as far as 98 feet (30 meters) from the bloom [source: Ladyman]. Through the night, hawk moths and other nocturnal insects feed on the nectar and cross-pollinate the flowers. In the morning, the flowers close up, never to open again.
New flowers may open on subsequent nights, but the festival of the night-blooming Cereus usually only lasts for a day or two. If the flowers are successfully pollinated, they develop an oblong, spiny, red-orange fruit. The plant grows from a tuberous taproot that's edible. Cereus greggii may provide an evolutionary link between a woody, non-succulent predecessor and modern succulents.
Night-blooming Cereus can be grown as a houseplant. It's easy to root stem cuttings, but it's a protected species, so don't go trolling the deserts for one. Get a 2 to 4-inch (5 to 10-centimeter) cutting from a friend, put it in sandy soil and moisten it. It should root within six weeks, but it will be two or three years before it's mature enough to bloom. To encourage flowering, put the plant outside under filtered light during the summer and fertilize it monthly from May to August. Water it regularly, but let it dry out between watering.
During the winter, keep it hungry and dry; don't fertilize it and let it go for longer periods between watering. "This is the season where you want the plant in a spare bedroom -- getting needed sunlight, but out of sight," advise the specialty gardeners at the University of Arkansas Cooperative Extension Service [source: University of Arkansas]. It's a homely plant when not in bloom.
Lovely flowers with unique survival adaptations grace the next few pages.
When the soil is too poor to provide enough nutrients to sustain the plant, what's a poor flower to do? Turn carnivore, of course.
The first published documentation of the American Pitcher Plant, a native of southeastern coastal plains of North America, came from Florida in 1576. Much later, in 1793, noted American botanist William Bartram took the time to notice that vast numbers of insects got trapped in the little "pitchers" of the plant. It wasn't until 1887 that South Carolina physician and amateur botanist Dr. Joseph H. Mellichamp proved the carnivorous nature of Sarracenia through a series of experiments that conclusively showed that insects caught in the plant were digested and reabsorbed by the plant. Studies on this wondrous herb continue today.
The life-cycle of the American pitcher plant goes like this: Sometime between late February and May, depending on the species, lovely five-petalled flowers emerge from the ground. Non-lethal leaves appear shortly after the blooms. In yellows or shades from pale pink to red, the flowers nod downward from 1 to 3-feet (33-centimeter to 1-meter) stalks. The scented blooms last from one to two weeks, attracting bees to pollinate them. It isn't until the petals drop from the flowers (revealing attractive seed pods) that the deadly pitchers open. This delay protects the pollinators from being devoured before they help create the plant's next generation.
Growing upright from the sandy, nutrient-sparse ground, the pitchers themselves could be mistaken for flowers. Many sport a ruffled "umbrella" over the opening of the tube. Red veins contrast with the green plant, making attractive and interesting patterns. The appealing colors lure insects to the pitcher, which contains sweet nectar.
It's here that the plot takes a sinister twist. The nectar the pitcher plant offers up is as deadly as Abby and Martha Brewster's elderberry wine. The nectar contains a narcotic, coniine, which causes paralyses and, like the arsenic in the old sisters' "charity" wine, can cause death. The drugged insects fall into the tubular pitcher. Because of the combined effects of the drug and the structure of the pitcher, they can't crawl out. In the bottom of the pitcher, the plant cooks up a soup of digestive acids and enzymes that break down the soft parts of the bugs. When the bug is as liquefied as it's going to get, the plant reabsorbs the soup. This is how it gets the nitrogen, potassium, phosphorous and other nutrients that it needs, but can't draw from the poor soil it grows in. Ants, flies and wasps are some of the insects that fall prey to the American Pitcher Plant.
Of the original Sarracenia population in the southeast, only about 5 percent remains [source: D'Amato]. Pitcher plants take years to mature, but you can cultivate them in your garden. There are many curious and beautiful varieties and a host of hybrids. You can start them from seeds or rhizome cuttings, as long as the rhizome has a few roots attached.
Sarracenia need a light, sandy soil. Carnivorous plant expert Peter D'Amato recommends a half-and-half mixture of sand and peat in plastic or glazed ceramic pots. A southeastern bog plant, they need wet soil and full sun with warm summers and mild winters. If you live in a temperate climate, you can plant them outside in a bog garden. The plants will experience three to four months of dormancy in the winter, but in the summer, they'll turn into "gluttonous pigs," according to D'Amato. Indoor plants may need supplemental hand feeding of crickets or dried insects.
If you're intrigued by the pitcher plant, keep reading to learn about the plant that Charles Darwin claimed interested him more than the origin of all the species of life on earth.
Sundews range from the penny-sized pygmy species to the "giant" (Drosera dichotoma) that can reach 4 feet (1.2 meters) in diameter. The five-petalled flowers are large relative to the size of the plant. They typically are white to pink, but some groups have orange, red, yellow or violet blooms. Most flowers are flat with rounded petals, but the profusely blooming lance-leafed Drosera adelae has star-like red flowers with contrasting white stamens encircling a yellow pistil. In most species, the flowers bloom sequentially on pendant columns, beginning with the flower at the base of the column and moving toward the tip. Depending on the plant, stalks reach lengths of a few inches to 1 to 2 feet (30 to 61 centimeters) [source: D'Amato]. Many self-pollinate, but a few need cross pollination.
As lovely as the flowers are, the true interest of the plant lies in the leaves. These are covered in "hairs" tipped with a gland that secrets sticky goo. Most hairs are red, but on some sundews they are transparent with a red gland at the tip. The goo looks like dew glistening in the sun and lures insects in for a drink. In 1578, English botanist Henry Lyte observed that the plant seemed to grow dewier as the sun grew hotter.
When insects land on the sundew, they get stuck in goo, a circumstance that prompts them to thrash about in an effort to get free. The movements bring the bug into contact with more sticky-tipped glands, until it's effectively cemented to the plant. The hair-like tentacles then close around the insect and begin to digest it.
Sundews are native to North American bogs, but the highly adaptable 130,000 species thrive or at least survive on nearly every continent [source: D'Amato]. They can be found wherever there are wet, low-nutrient soils, whether that's in the seasonal, semi-frozen bogs of Siberia or the extreme southern regions of New Zealand and South America.
If you can see a sundew adding interest to your future, here are some tips to keep it thriving. If you plant Drosera in your garden, chose species whose native habitat is similar to what they'll experience in the environment you provide. If you live in warm-temperate, subtropical or Mediterranean climates, you'll have the widest variety of sundews to choose from.
Some species, such as the cape sundews, rosetted sub-tropical natives, and giants like Drosera regia and D. multifida, are amenable to life on a windowsill. Provide them with cool, humid conditions and morning sunlight. Chose small species for terrariums. These little creatures need to be placed within inches of a fluorescent bulb to achieve their maximum potential. And don't forget to feed them.
As innocuous looking as it sounds, the butterwort hides a slippery secret in plain view. Lip-like flowers with a spur end (that probably inspired "Little Shop of Horrors" screenplay writer Charles B. Griffith) rise on simple stems several inches (centimeters) into the air. But this small plant's deadly secret isn't its hungry-looking bloom. The real danger lies in the slick, tongue-shaped leaves that nestle close to the ground.
Pinguicula means "little greasy one" in Latin, and the leaves do have a greasy feel. Strangely, the greasy substance is glue, secreted by thousands of nearly invisible glandular hairs. These glands work to secure insects; a secondary gland comes into play once a bug is caught. The sessile glands exude acids and enzymes that coat the insect and dissolve its soft parts. The leaves of the butterwort are slightly upturned on the edges, and some temperate climate species can increase the curl while the plant is digesting prey. It usually only happens when the plant is dealing with larger insects. Researchers don't think this slight movement has the same function that leaf movements in the sundews have; instead, it probably serves to keep the abundance of digestive juices from dripping off the edge of the leaf before the plant can reabsorb them. A deep pool of juices is more effective for digesting large insects, and loss of the juices would also mean loss of the nutrients dissolved into them.
Butterworts or "pings" exist in most reaches of the Northern Hemisphere, with the most spectacular species being found in Mexico. There are about 70 species, many only recently discovered [source: D'Amato]. They typically have a circular, rosette form measuring a few inches (centimeters) in diameter, and they may have a musty or earthy smell. The flowers bloom in spring and can last for months. Depending on the species, flowers are funnel-shaped, cupped or flat, and some have beards. There is only one butterwort, P. laueana, that's known to have reddish flowers; most bloom white, pink, purple or yellow.
Pings are popular and easy-to-grow houseplants. You can start them from seeds or buds, and Mexican varieties will root from leaf cuttings. All pings need perpetually moist soil and have a dormant or semi-dormant period in the winter. Put them outside for warmer months so their pollinators, hummingbirds and long-tongued insects, can get to them. And don't forget to feed them when they're indoors. Their natural prey can be supplemented with fruit flies, ants and dried insects.
Carnivorous plants aren't restricted to land. The next page features a ravenous aquatic species.
Little floating stomachs would be an apt description of bladderworts, the largest and most wide-spread genus of carnivorous plants. These minute aquatic beasts are found from Alaskan swamps to tropical regions, making their homes in wet, mossy trees, fast streams and seasonal deserts. When drought strikes, they transform into tiny tubers to ride it out.
The prolific and varied blooms of Utricularia can look like miniature orchids, irises, pea blossoms or buttons. Some of the 214 known species even have free-form blooms that can't be likened to anything particular [source: D'Amato]. They flower in a wide range of colors and color combinations.
Lurking beneath the lovely blossoms, scattered among hair-like stems, are hundreds of pinhead-sized carnivorous bladders trailing trigger hairs into the water. The hairs alert the bladder that prey is near. Bladderworts feed on small aquatic insects such as water fleas, and larger unfortunates like mosquito larvae and tadpoles.
First, the prey tickles the trigger hair. Lightning fast, the bladder opens a trap door and sucks the animal inside, where digestive juices dissolve it. The larger meals don't fit into the bladder. They get caught like an animal in a foot trap and are digested slowly, by millimeters. When the part inside the bladder is fully digested, the trap door opens and sucks a little more of the still-living victim inside. This continues until the entire animal is absorbed. The strong vacuum of the trap and the speed with which it acts eliminate any chance of escape.
As sinister as they are, plant enthusiasts value bladderworts for their flowers. They're rootless, their stems and leaves are unimpressive, and when not blooming, the plant looks like slime. But when they are blooming, they're irresistible. All types, aquatic, terrestrial and epiphytic (growing on another plant, but not as a parasite) are easy to grow as houseplants. Orchid bark and sphagnum moss create a good home for epiphytic plants. Use a half-and-half mix of peat and sand for terrestrial species, and add a cup of peat for each gallon of water your aquatic species will inhabit [source: D'Amato]. Most species need sunny conditions to thrive and flower. You can feed and water them at the same time if you use pond water. It contains the microscopic creatures Utricularia depends on for survival.
Would you rather grow something unique, but less hungry? Consider the big, brilliant, definitely out-of-the-ordinary flowers on the next two pages.
Hummingbirds don't mind that Kniphofia resembles a giant toilet brush atop a leafless cane. They love the dozens of brilliant orange and yellow flower tubes that adorn the stalk. Kinder common names for this plant include Torch Lily and Red-Hot Poker.
Kniphofia is simply a garden flower, without any of the quirky characteristics or bad habits of the flowers we've seen on previous pages. But its powerful appearance is sure to add interest to your landscape and draw comments from your neighbors.
The African native is closely related to aloe, but it doesn't have any healing juices. Two to 5-foot (1.5-meter) tall flower stalks grow from clumps of evergreen grass-like leaves. The leaf clumps resemble tall ornamental grasses, and may spread to 3 feet (1 meter) in diameter [source: The Garden Helper]. If you plant a mix of early, mid-season, and late blooming varieties, you can have torch lilies adorning your yard from May to October.
Kniphofia like temperate gardens; they're hardy in USDA zones 5 to 10 if you provide winter protection in the colder regions. They need full sun and neutral soil with good drainage. Hummingbirds aren't the only wildlife who take nourishment from red-hot pokers, but the slugs and snails who feed on them will do damage. They make good cut flowers, and removing older blooms actually encourages the plant to produce more flowers.
You can increase your torch lily display from seeds or by plant division. If you want to start new plants from seed, let some flowers stay on the stalks near the end of their blooming season. Collect the seeds and chill them (with some moisture) in the refrigerator for six weeks before you try to germinate them. After the chill period, you can start the seeds indoors at anytime, and you should start them early, since they can take up to three months to germinate.
If you want to divide mature plants, do it in either spring or fall. You'll get a new plant faster this way, but you'll sacrifice blooms for the next season. Kniphofia take two or three years after division to recover their full flowering potential. So when your neighbors beg you for a cutting from your glorious torch lily, offer them seeds instead.
If you're into the blues, sea hollies will hit the top 10 in your garden. This odd-looking flower sports an elongated cone of tiny blue flowers on a platform of spiny blue-green bracts at the top of metallic blue stems.
Also known as Rattlesnake-Master, Sea Holm, Spiny Cilantro and Miss Wilmott's Ghost, these hardy and semi-hardy perennials bloom in the latter half of summer. They're big plants, ranging from 18 to 36 inches (46 to 91 centimeters) high with a one-foot (30-centimeter) spread [source: Deem-Reilly]. They appreciate a little help through dry periods, and may need staking if you live in a windy area, but they're tough enough to look after themselves for the most part. They're hardy to USDA zone 5.
Sea hollies are native to Iran and the Caucasus, but some species grow wild in the United States. They're related to Queen Anne's lace, parsley, fennel and anise. Although they have no fragrance, Eryngium attract butterflies. The flowers make an interesting addition to fresh-cut displays and dry well for dried arrangements.
Sea hollies need full sun and moist soil with good drainage. They grow from a deep taproot. This helps them survive droughts, but it makes them difficult to divide or relocate. Fortunately, they're easy to grow from seed. It may take a while to get them started, though. Collected seeds should be refrigerated for three weeks. Once planted in the garden, it may take up to 10 weeks before the seeds germinate. New plants probably won't bloom in their first year. Before you put a lot of effort into this method, make sure that the sea holly you collect seeds from is a naturally occurring species. Hybrids or cultivars may be sterile, and are unlikely to grow true to the parent plant if they do germinate.
A new website is designed to bring farmers and heirloom seeds together. HowStuffWorks takes a look at why seed saving is more important than ever.
Related HowStuffWorks Articles
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- Bawden-Davis, Julie. Flower Gardening: A Practical Guide to Creating Colorful Gardens in Every Yard. New York: Readers Digest, 2004.
- Calyx Flowers. "Sea Holly." (Accessed 10/08/2009). http://www.calyxflowers.com/Floral-Library/Content/Sea-Holly.aspx
- Casey, Carol. "Carnivorous Plants Whet Appetite for Learning." Washington College Magazine: Spring 2000. (Accessed 10/08/2009). http://www.washcoll.edu/wc/news/washmag/spring2000/00_spring_13.html
- Chafin, Linda G. Field Guide to the Rare Plants of Georgia. Athens: The State Botanical Garden of Georgia and the Georgia Conservation Alliance, 2007.
- Chittka, Lars with Avi Schmida, Nikolaus Troje, and Randolf Menzel. "Ultraviolet as a Component of Flower Reflections, and the Colour Perception of Hymenoptera." Elsevier Science Ltd. 1994. (Accessed 10/12/2009). http://www.biomotionlab.ca/Text/chittka_VR_94.pdf
- D'Amato, Peter. The Savage Garden: Cultivating Carnivorous Plants. Berkeley: Ten Speed Press, 1998.
- Darwin, Charles. Insectivorous Plants. New York: D. Appleton and Company, 1875. Project Gutenberg. (Accessed 10/08/2009). http://www.gutenberg.org/etext/5765
- Deem-Reilly, Terry. "Sea Holly: Eryngium." Colorado State University Cooperative Extension, Denver. January 4, 2009. (Accessed 10/08/2009). http://www.coopext.colostate.edu/4DMG/Flowers/Perenls/seaholly.htm
- Earlham College. "The Genus Rafflesia." Biological Diversity 2003. (Accessed 10/11/2009). http://www.earlham.edu/~givenbe/Rafflesia/rafflesia/biodiv2.htm
- Economic Research Service. "Floriculture and Nursery Crops Yearbook -- Summary." United States Department of Agriculture. September 28, 2007. (Accessed 10/07/2009). http://www.ers.usda.gov/Publications/Flo/2007/09Sep/FLO2007s.txt
- Greer, Germaine. "Country Notebook: Ellen Wilmott." Telegraph.co.uk: April 19, 2003. (Accessed 10/15/2009). http://www.telegraph.co.uk/gardening/gardenprojects/3310290/Country-notebook-Ellen-Willmott.html
- Kanapaux, Bill. "Evolution of the First Flowers." The Florida Museum of Natural History. Natural History Magazine, August 8, 2009. (Accessed 10/06/2009). http://www.naturalhistorymag.com/partner/florida-highlight-sept
- Kew Gardens. "Titan arum." Kew Garden website. (Accessed 10/07/2009). http://www.kew.org/plants/titan/history.html
- Ladyman, Juanita A.R. "Cereus greggii Englemann." JnJ Associates. (Accessed 10/12/2009). http://www.fs.fed.us/global/iitf/pdf/shrubs/Cereus%20greggii.pdf
- Leeward Community College. "Animal Pollinators." Plants in the Hawaiian Environment. University of Hawaii Distance Education Web. (Accessed 10/12/2009). http://emedia.leeward.hawaii.edu/millen/bot130/learning_objectives/lo07/07.html
- Lloyd, Christopher. Color for Adventurous Gardeners. London: Firefly Books, 2001.
- Marent, Thomas with Ben Morgan. Rainforest. New York: DK Publishing, 2006.
- Markham, Kenneth R. and Stephen J. Bloor, Rob Nicholson, Paul Rivera, Melvin Shemluck, Peter G. Kevan, and Charles Michener. "Black Flower Coloration in Lisianthius nigrescens: Its Chemistry and Ecological Consequences." July 6, 2004. (Accessed 10/08/2009). http://www.znaturforsch.com/ac/v59c/s59c0625.pdf
- Raffles Museum of Biodiversity Research. "Sir Thomas Stamford Raffles, 1781-1826." Department of Biological Sciences, University of Singapore. 2000. (Accessed 10/11/2009). http://rmbr.nus.edu.sg/history/raffles.htm
- Royo, A.R. "Night-Blooming Cereus." Exploring the Southwest Desert USA: July 1999. (Accessed 10/08/2009). http://www.desertusa.com/mag99/july/papr/nbcereus.html
- Souza, D.M. Freaky Flowers. New York: Franklin Watts, 2002.
- Stern, Marc. "Kniphofia Moench." Witwatersrand National Botanical Garden: July 2002. (Accessed 10/08/2009). http://www.plantzafrica.com/plantklm/kniphofias.htm
- The Garden Helper. "How to Grow Torch Lilly . . . Red Hot Poker." November 5, 1999. (Accessed 10/08/2009). http://www.thegardenhelper.com/tritoma.html
- Thomas, Paul A. "Growing Orchids." Horticulture Fact Sheet H-93-013. The University of Georgia College of Agricultural and Environmental Sciences Cooperative Extension Service. (Accessed 10/07/2009). http://pubs.caes.uga.edu/caespubs/horticulture/orchids.html
- University of Arkansas. "Night Blooming Cereus." Division of Agriculture. Cooperative Extension Service. July 15, 2009. (Accessed 10/08/2009). http://www.arhomeandgarden.org/landscaping/SpecGardening/night_blooming_cereus.htm
- University of California Museum of Paleontology. "Introduction to Anthophyta, the flowering plants." University of California, Berkeley, 2009. (Accessed 10/06/2009). http://www.ucmp.berkeley.edu/anthophyta/anthophyta.html
- University of Connecticut. "Amorphophallus titanium." Ecology and Evolutionary Biology Plant Growth Facilities. College of Arts and Sciences. October 6, 2009. (Accessed 10/07/2009). http://florawww.eeb.uconn.edu/199500115.html
- Wahlert, John H. and Mary Jean Holland. "Division Anthophyta (Angiosperms): Flowering Plants." Baruch College, City University of New York. September 22, 2007. (Accessed 10/06/2009). http://faculty.baruch.cuny.edu/jwahlert/bio1003/anthophyta.html