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Learn more about the plants and gardens at the Chicago Botanic Garden.

Can Spike’s “Perfume” Be Captured in a Jar?

A Student Asks, Our Scientist Answers

Karen Z. —  August 28, 2015 — 3 Comments

Of the many Spike-related questions asked by visitors this week, our favorite came from 8-year-old Prairie! In the video below, Prairie wants to know, in essence, if she can transport Spike’s malodorous odor from the Chicago Botanic Garden to her classroom.

Good question, Prairie!

Conservation scientist Dr. Shannon Still has a fascinating response. Dr. Still will attempt to pollinate Spike’s flowers during bloom with pollen shared by our friends from The Huntington Library, Art Collections, and Botanical Gardens, and Denver Botanic Gardens.

Prairie, your experiment with scent would make a great science project! If you come to the Garden on the night Spike blooms, perhaps you’ll get to see Shannon Still working on “Operation Pollination.” Introduce yourself if you’re there!


©2015 Chicago Botanic Garden and my.chicagobotanic.org

One of the top questions we have been getting about Spike the titan arum is “How do you know how much water to give him?” 

PHOTO: Titan arum (Amorphophallus titanum) a mere few days from bloom.

It’s nearly showtime! The outer bracts have fallen away, and the spathe is now showing a slight purple cast.

The care and feeding that we have given Spike and his fellow titan arums—our collection of nine Amorphophallus titanum growing in our production greenhouses—is very specific!

Yes, the cultivation requirements for these plants are strict. Titan arums require well-maintained conditions of high humidity and high temperature—similar to their natural conditions in the tropical rainforests of Sumatra. Therefore, the cultivation is not particularly suitable for most beginners or homeowners with minimal greenhouse facilities.

Watering the bloom

During Spike’s flowering stage, we make sure the soil is evenly moist at all times. This is important to continue flower development and prevent the spathe (the frilly modified leaf) from drying out or not opening. We also pay special attention to air humidity—we try to keep the humidity between 75 to 90 percent saturation at all times. How? We keep the floors wet and prevent excessive venting in the greenhouse.

PHOTO: A hygrometer in Spike's planter measures relative humidity in the greenhouse.

A hygrometer in Spike’s planter measures relative humidity in the greenhouse.

Watering for leaf growth

Spike and the rest of the collection have grown through many leaf and dormancy cycles into larger corms (a type of underground tuber or bulb). It would seem that tending the growing corms would be about as complicated as a typical bulb, but a close eye must be kept on how the corms are watered to prevent them from drying out or rotting. As the leaves grow larger each growth period (12 to 18 months), their increasingly larger corms may prevent the soil beneath them from becoming wet. Increasing watering to make sure the soil is kept moist at the bottom of the tuber could cause the corm to rot, as most of its roots develop on the upper surface. The growing medium must be evenly moist at all times, but not wet, and the soil should never dry out completely, especially at the start of leaf development. Using a loose medium and a layer of gravel drainage in the planters ensures that water reaches all parts of the corm without flooding it. Finally, we repot the corms—a lot—to make sure the soil stays evenly moist, and to give them room to grow! 

Yes, we went through a lot of pots…

PHOTO: An Amorphophallus titanum corm.

When repotting very large corms, it is important not to lay them directly on a hard surface. Their own weight can cause damage to the bottom of the corm and cause rotting. Photo by Georgialh (Own work) [CC BY-SA 4.0], via Wikimedia Commons.

Spike was repotted many times as the corm continued to grow larger each season. In fact, several times the pots or containers that the plant was growing in would crack or break as the swelling corm beneath the soil surface would “push” outward and damage its container. Last fall, we finally had our carpenters here at the Chicago Botanic Garden make big 42″-by- 42″ wooden crates as a more permanent home to grow Spike and several others in our collection. At the end of each dormancy cycle, we carefully lift the corms, inspect them for pests or rot, and remove any unwanted new bulbils that may have formed. When moving these corms to their new homes, we provided extra drainage at the bottom of the crates by amending the soil with more perlite at the bottom and a layer of gravel.

How hot is it in here, exactly?

Not surprisingly for a Sumatran plant, Amorphophallus titanum prefer to be grown at temperatures between 70 to 85 degrees Fahrenheit during the day and 68 to 80 degrees at night—pretty warm, and without a lot of temperature fluctuation. Temperatures above 90 degrees or extreme cool temperatures may damage the foliage or flower, so we are keeping a close eye on Spike as visitors come to check on his progress.

The future’s so bright…

Spike also needs a lot of sunlight—both in leaf and flower form. We provide minimal shading to our collection (enough to prevent foliar damage), and only during the hottest summer months. Does that mean we need additional lighting to compensate for Chicago being so far north of the equator? Actually, no. No additional lighting or day length control have been necessary. The lights currently surrounding Spike in the greenhouse are for our time-lapse cameras, to make sure our star is lit evenly on his performance night!

Does Spike need a lot of fertilizer?

Definitely! Titan arums require high levels of fertilizer to be applied on a regular basis while in the leaf stage. We fertilized at every other watering, especially during the summer months, and reduced fertilization during the colder winter months. When we determined the emerging shoot of Spike was indeed a flower, however, fertilization ceased.

Are you sure you don’t know exactly when Spike will open?

We’re sure we don’t know for certain. We have key factors we look for, like the bracts (outer leaves) shriveling up and falling away 48 hours before a bloom. But this is not always the rule—in some cases, blooming is what makes the bracts finally fall away from the flower! In the end, only Spike knows when he’ll bloom.

PHOTO: Spike the titan arum on display at the Chicago Botanic Garden.

Spike’s fans check in in his progress—it won’t be long, now!

As you can see, the cultivation of our Amorphophallus titanum collection can be somewhat challenging! Providing them with the unique cultural requirements to get them to live long enough and to eventually bloom is a mighty task. However, all the extra “TLC” given by our greenhouse staff will be well worth the long wait to see Spike bloom in just a few days.


©2015 Chicago Botanic Garden and my.chicagobotanic.org

About That Smell…

Tim Pollak —  August 15, 2015 — 8 Comments

The night Spike blooms will thrill us all in the semi-tropical greenhouse, with its breathtaking flower…accompanied by a titanically rotten smell. 

“Your heart is full of unwashed socks, your soul is full of gunk, Mr. Grinch. The three words that best describe you are as follows— and I quote: stink, stank, stunk!”
—Dr. Seuss

“Titan Tim” Pollak here once again, with an update on Spike, our still-growing titan arum. Spike continues to get bigger, not only in height, but also in girth! What we’re really curious about, however, is the aroma.

The stench is one of the cool reasons to stay up late and come to the Garden that night—we’ll be open from 9 p.m. to 2 a.m.

Here’s what to expect in terms of scent:

What an "arum-atic" combination of scents!

What an “arum-atic” combination of scents!

  • As the spathe gradually unfurls, the spadix releases powerful odors meant to attract pollinators. The potency of the aroma gradually increases from late evening until the middle of the night and then tapers off as morning arrives.
  • Analyses of chemicals released by the spadix show the “stench” includes dimethyl trisulfide (like limburger cheese), dimethyl disulfide, trimethylamine (rotting fish), isovaleric acid (sweaty socks), benzyl alcohol (sweet floral scent), phenol (like Chloraseptic), and indole (like mothballs).
  • The titan arum’s odor has been described in many other terms as well: rotting flesh, rancid meat, rotting animal carcass, old dirty socks, and even the smell of death itself, which accounts for the plant’s common name, the corpse flower.
  • In its natural habitat on the island of Sumatra in Indonesia, the “fragrance” is used to attract the carrion-eating beetles, dung beetles, and flesh flies that pollinate the titan arum. The inflorescence’s deep red color and texture contribute to the illusion that the spathe is a piece of meat.
  • During bloom, the tip of the spadix is approximately human body temperature, which helps the fragrance volatilize (turn to vapor) and travel long distances; the heat may also advertise that there’s a fresh carcass for insects to check out. 
PHOTO: Dung beetle (Catharsius sp.)

Carrion flies and dung beetles like this one (Catharsius sp.) think that stink smells great. Photo ©2012 via potokito-myshot.blogspot.com

A different view of ewwww!

Carrion beetles, dung flies, and flesh flies aren’t responding to the call of the titan arum’s scent because they want to be pollinators—they’re responding because they want a good environment in which to lay their eggs. 

In the wild, mama beetles and flies lay eggs on dead animals or animal feces knowing that the larvae that hatch will have an immediately-available, rich source of food.

In its natural rainforest habitat, the titan arum has adapted to that fact. Over evolutionary time, it has developed the right scent to attract those insects—and, like many scented flowers, to deceive them with scent into acting as the unwitting spreaders of their pollen. 

Keep checking back for more on Spike’s progress!

©2015 Chicago Botanic Garden and my.chicagobotanic.org

Spike’s Wild World

Tim Pollak —  August 14, 2015 — Leave a comment

“Where does a titan arum come from?” That’s a question we heard a lot from Spike’s visitors this past weekend. 

MAP: Sumatra, highlighting the western mountain range of the island.

Titan arum occurs throughout the Barisan mountain range in West Sumatra, Indonesia.

The titan arum, native to the rainforests of the island of Sumatra in Indonesia, was first “discovered” by Italian botanist Odoardo Beccari in 1878. On August 6, 1878, he first observed the leaves and fruits of a plant (interestingly, August 6 is the date we put Spike on public view!). Several weeks later, Beccari saw a flowering plant for the first time. He sent a few tubers and seeds to Florence, Italy, but the tubers all perished; a few seeds, however, eventually germinated. One of those seedlings was sent to the Royal Botanic Gardens, Kew, in England. There, in 1889, 11 years after its discovery, a titan arum plant flowered for the first time outside its tropical home.

No one knows how common the titan arum is in the wild. Many suspect it is endangered. Its only known habitat is the rainforest of Sumatra, which is being steadily eroded by deforestation for palm oil production, by pollution, and by human encroachment. The corms are also being dug up for food—and by collectors or poachers.

PHOTO: Kerinci Seblat National Park, Sumatra, Indonesia. Photo by Luke Mackin.

Kerinci Seblat National Park in Sumatra, Indonesia, features dense rainforest. Photo by Luke Mackin

Also contributing to their demise is the fact that many species in the genus Amorphophallus, including the titan arum, are highly endemic. This means that they are only found in relatively small, restricted geographical areas. If the rainforest home of these species is destroyed, we will continue to see their numbers decrease.

PHOTO: Titan arum (Amorphophallus titanum) in bloom in its native habitat in Sumatra. Photo © Luke Mackin/Wild Sumatra

Finding a titan arum (Amorphophallus titanum) in bloom in its native habitat is a thrilling experience. Photo © Luke Mackin

What can we do to help conserve the titan arum and similar plants? Start by learning more about tropical rainforests, and the impact of deforestation in these areas. Support your local botanic gardens, arboreta, and universities where scientists are studying endangered plant species and promoting the importance of plant conservation.

The titan arum (Amorphophallus titanum) is one of the plant kingdom’s most spectacular phenomena—and spectacular plants help us all to realize the incredible complexity and diversity of the natural world.

"See Spike" button corpse flower
Become a Garden member and support the world’s spectacular plants, like Spike, at the Chicago Botanic Garden: We cultivate the power of plants to sustain and enrich life.

We are getting closer to bloom time! Check our website, and #CBGSpike on social media to stay on top of bloom updates! When Spike blooms, we’ll stay open until 2 a.m.!


©2015 Chicago Botanic Garden and my.chicagobotanic.org

“Titan Tim” Pollak here, with today’s update on Spike, our first-ever corpse flower.

PHOTO: The corm of an Amorphophallus titanum: after a dozen or so years, it's large enough to produce a bloom!

The corm of an Amorphophallus titanum: after a dozen or so years, it’s large enough to produce a bloom!

Spike just keeps on growing at the Semitropical Greenhouse, and visitors are loving it. As they learn more about the coming bloom from the docents posted there, one of the most frequently ask questions is, “How could you tell this time that Spike was a flower?”

How could we tell that Spike was going to be a flower? It’s tricky. Even the most experienced botanists have a hard time determining whether a titan arum shoot is a flower or a leaf at first. But soon enough, the clues start to add up.

PHOTO: An Amorphophallus titanum shoot to the right of a leaf stalk provides comparison for determining the slight bulge which could mean a flower bud.

An Amorphophallus titanum shoot to the right of a leaf stalk provides comparison for determining the slight bulge, which could mean a flower bud.

PHOTO: The emerging Amorphophallus titanum plant looks leafy, unlike the smooth spadix which emerges from a flower bud.

The emerging Amorphophallus titanum plant looks leafy, unlike the smooth spadix that emerges from a flower bud.

  1. Spike is 12 years old. We know from other botanic gardens and conservatories that titan arums take a decade or more to send up their first flower shoot. We’ve been tending to this corm for about 12 years, so the timing was right.
  2. Is the corm big enough? The smaller the corm, the less power it has stored to send up the titan’s huge flower. This corm is about the size of a beach ball—definitely an appropriate size for flowering.
  3. A bulge at the base. It’s subtle, but a slight swelling at the base of the newly emerged shoot signaled something different than a leaf.
  4. A little off center. At 18 to 20 inches tall, we noticed a telltale sign: the tip of the shoot was off-center. While leaf shoots are true to center, we knew that a flower shoot powers up in a slightly different way. Again: it’s subtle but telling!
  5. Horticultural intuition. Both Deb Moore—our indoor floriculturist who tends to our nine titan arums—and I felt that the overall look of the shoot was different than what we’d experienced before with shoots that become a leaf. (While the titan’s non-bloom form may look like a stalk with multiple leaves, it is actually a single, giant leaf!) Like every gardener, you develop a sense for what’s “normal” and what’s not when it comes to your plants. We both thought that this shoot was somehow different, and it was!

PHOTO: While these may look like branches and leaves, each of these Amorphophallus titanum are actually single-leaf plants.

While these may look like branches and leaves, each of these Amorphophallus titanum are actually single-leaf plants.

Our final “sign” was to ask the experienced titan growers from other institutions. We called upon the folks at the Huntington Library, Art Collections, and Botanical Gardens in San Marino, California; Smithsonian Gardens in Washington, D.C.; Phipps Conservatory and Botanical Gardens in Pittsburgh, Pennsylvania; and Missouri Botanical Garden in St. Louis, Missouri, for their opinions and expertise. Their final confirmations gave us the thumbs up to go public with the big news that Spike would soon blast into bloom!

Like first-time parents, we are learning as we go. I can’t tell you how excited we all are in the production greenhouses—it’s a thrill to watch a plant that you’ve tended for so long finally get ready to flower! Visitors’ anticipation is rubbing off on us, too—we’ll be standing right next to you as the titan arum heads into its big night of bloom!

I’ll keep you posted…


©2015 Chicago Botanic Garden and my.chicagobotanic.org