What's That Smell? Corpse Flowers!
There's nothing more wonderful than something in nature that breaks all our standard rules; naturally the carnivorous plants I obsess over are on the top of that list for me, but there's another group of plants that I've more recently begun to grow addicted to that also like to mess up what we think is the natural state of things...
When one thinks of flowers, what typically comes to mind is a delicate, perhaps dazzling little disc of petals shrouded in brilliant colors and often beget with entrancing floral or fruity aromas. Daisies, roses, columbines, lupines...standards of the front yard display and familiar to all. But of course, just as there are hundreds of thousands of plant species out there, there are also thousands of ways those plants reproduce and attract pollinators to assist, and not all of those methods are cute and inviting to us.
Enter, the corpse flower:
Many people are familiar of course with Amorphophallus titanum, the Giant Arum that captures news attention whenever one blooms, but that is merely one of hundreds of different species of Amorphophallus found across the Old World tropics, and that genus merely one of dozens of genera found worldwide. Many of those related groups are in fact grown commonly as garden or houseplants (ie. calla lilies and jack-in-the-pulpits), and some of them have "normal" scents and growth habits, but the fun really comes in these groups that are truly different from our standards.
This post will focus on the species above shortly, but first, an overall introduction: the genus Amorphophallus collectively grows very strangely. Nearly all go through cycles of growth and dormancy, some of these cycles mediated by the climate the species is found in (seasonal habitats in Africa, Australia, or Indochina for example) while others which live in truly tropical locations like Sumatra and Borneo run through their dormant periods at random and with seemingly no discernible cues. When dormant, they survive underground as corms (or tubers, as the two terms collide somewhat in the structures formed by the aroids), specialized swollen underground stem sections that store nutrients for the next round of vegetative or floral growth. Oftentimes these corms will develop offshoots that can form new corms and plantlets.
When the plant breaks dormancy, typical habit is to send up a single leaf composed of a tall, thick petiole and a lamina at the top that branches out in all directions into several or even hundreds of leaflets; the appearance is not unlike that of a small tree, with the central trunk overshadowed by the umbrella of branches and leaves, but in this case it's all composed of just one singular branching leaf! Depending on age and species, this one leaf may be no more than a foot tall and wide, or may be more than 15 feet in height and nearly as broad, truly a wonder to behold. The petiole of the leaf is often decorated in elaborate mottled markings of various appearance as well, the pattern of which sometimes distinguishing between species, and the leaflets vary in structure and color somewhat too.
When large enough, occasionally the corm will not send up a leaf, but instead a truly bizarre inflorescence which earns the genus its collective name. On top of a stalk of varying length, a fleshy spathe develops (a modified bract) which surrounds the inflorescence proper that is composed of a thick spadix (the often inappropriate appearance of which earned the genus its Latin name Amorphophallus, aka "misshapen male reproductive organ") and dozens to hundreds of individual male and female flowers (contrary to popular belief, it is not a single flower but a composite of many). As the inflorescence unfolds, the female flowers become sticky and receptive and an odor of varying intensity (and often disagreeability) is released, attracting pollinators like flies and beetles. After a couple days the female flowers are no longer receptive, and the male flowers then mature and release pollen as the odor continues to attract pollinators. If pollination was successful, the spathe and upper odor-releasing section of the spadix will die back and the female flowers develop berries (the color of which are often highly attractive as well, from red to metallic blue etc.). The seeds inside the berries are different from most other plants, not possessing a protective outer covering and so requiring immediate good conditions to germinate once they are parted from the fruit of the berry.
Though it's not my first aroid to bloom (other posts to come to cover them), A. konjac is my first species of this genus so far to flower, and perhaps one of the most common and easily grown species to boot. And oh, does it earn the name corpse flower!
This species is well-distributed and highly variable, with many cultivars developed based on stem, leaf, and flower coloration and shape (I currently own two forms, the standard seen above and the cultivar 'Nightstick', named for a nearly black leaf petiole). It is a native of Yunnan Province in southern China (bordering Myanmar, Laos, and Vietnam), though for a number of reasons is now grown across many tropical and subtropical regions of the world (believe it or not, this and many other species of aroid are grown as food crops! The corms are harvested for cooking). The corms may reach more than 10" in diameter at maturity (perhaps far larger in very mature specimens) and weigh several pounds. Leaves can exceed 5 feet in height and more than 4 feet in diameter; the petiole is highly variable in appearance and may be mottled in shades of pinkish cream and dark green, lighter greens and yellows, or solid purplish black or green depending on the variety. Leaflets are a little more standardized, ovate to broadly oblanceolate with tapering, filamentous tips, and shades of light to deep green marked with distinct veins throughout.
The flower stalk is of course the most striking feature, and if produced is typically earlier in the year than a leaf will be. The entire structure (stalk and inflorescence) can reach more than 6 feet in height, with a mottled stalk and a broad, cup-shaped spathe that on the exterior starts off mottled in greens and tan or pink at the base and fades into a light to deep reddish-maroon above. The spathe can be more than a foot and a half across and up to 2 feet long, roughly arrowhead shaped above the cup base, and the interior is almost entirely deep cherry red to purplish black. The texture too resembles something like flesh
The spadix rises high above the spathe itself, up to 2 1/2 to maybe 3 feet long and shaped like the end of a spear, and decked out in the same maroon shades as the spathe. When the flower is mature, tiny droplets of liquid can be seen forming all along this spadix, releasing that pungent odor that smells more or less like something died (and from personal experience, it's strong enough to permeate through plastic bags used to cover the smell). This odor of course serves to attract carrion flies, beetles, and any other insects that might be interested in munching on a deceased animal; all they find, of course, is a trick here, but even in the still winter climate that mine bloomed in that didn't stop all manner of beetles and small flies from making their way to this bloom, and some stuck around for a while.
Fascinatingly, this and several other species of corpse flower also are thermogenic; to help spread the odor, the flowers actually heat up particularly at night.
Below the main section of the spadix the flowers themselves are visible; female flowers are found in the very based of the inflorescence cup and males above. Female flowers are receptive first, covered in a sticky fluid meant to capture pollen, and the narrow cup of the spathe base helps force visiting insects right into contact with the exposed stigmas.
After a few days the female flowers lose their stickiness and the males mature, releasing pollen and coating any newly arriving insects (or the poor saps that didn't escape the cup of the spathe earlier), so that they may take pollen out to another, hopefully more recently flowering individual. A. konjac is a species that requires two separate clones to produce seeds, so the differential flowering period is an evolutionary tactic to ensure cross-pollination. After the bloom is spent, if pollination was successful then the plant will focus energy on ripening the berries produced, and a leaf will be made in the next growing season; otherwise, the flower stalk may die off entirely and a new leaf form to replenish the corm of resources lost during blooming.
A. konjac is quite the easy species to keep; while some other species in the genus require very warm, humid conditions or to be kept just at the right moisture level in their dormant periods, this one couldn't care less what conditions you put it in just so long as you don't subject it to a deep freeze (some are even grown in warmer temperate regions in-ground). A good, well-drained and rich soil in a pot at least greater in diameter than the tuber at full size (that means a pot at least a foot across, if not bigger) is best, and during growth an occasional fertilizer treatment with watering is needed for proper corm development. When the flower or leaf dies back, the soil can be allowed to go entirely dry, and the corm can even be stored or even allowed to flower while not in soil at all. Many small offshoots are often produced each year as well, and new plantlets can be grown for a time with the parent or separated into their own pots to grow out once the offshoot splits from the main corm fully.