12 August 2008

Deceptive petals: 7 orchid mimics

Like the Genovese and the Gambino, the Orchidaceae are an intimidating family. With about 25,000 species, it's also the largest family of flowering plants. This does not make it any easier to identify a member, however. So let me ask you: how do you know when a flower is an orchid? Most people will probably answer, 'you can tell by the differently coloured lip'. This would be a mistake. Many plants with brightly coloured lips aren't orchids at all. Many others just have a gestalt that screams 'orchid' in hot pink tones, but you'd be wrong again. Botany is sometimes confusing. Let's take a look at a few examples of flowers that seem to mimic those of the orchids.

Bauhinia blakeana [Fabaceae - the Legume family]. It's easy to see why this is called the Hong Kong orchid tree, for the resemblance to an orchid blossom is rather striking. In 1880, Sir Henry Blake - then British Governor of Hong Kong and a keen botanist - discovered the plant growing near the ruins of a building on the shore of Pok Fu Lam. It has since become the floral emblem of Hong Kong. A popular tree for highway medians and parking lots in hot cities, it's large heart-shaped leaves make it attractive even when out-of-bloom.

Alpinia zerumbet [Zingiberaceae - the Ginger family]. Many members of this gorgeous plant family produce flowers that appear orchid-like, complete with glowing lips in the correct, lowermost orientation. Unlike orchid flowers, those of ginger do not possess a column, the central structure formed from the fusion of male and female parts. Shell ginger is a good example. This Chinese evergreen rapidly forms large clumps of lush tropical foliage when grown in frost-free areas with partial shade.

Tacca chantrieri [Dioscoreaceae - the Yam family]. After seeing the diverse array of
black orchids out there, it is tempting to classify this sinister thing as an orchid. The bat flower, as it is affectionately known, actually belongs to the plant family that includes yams and other herbaceous vines. What appears to be large, darkly coloured petals are in fact involucral bracts, and not floral structures at all, just like the festive red 'petals' of the poinsettia. The real flowers are the cup-shaped structures within, surrounded by distinctive whiskers. If you can grow Phalaenopsis orchids really well, this Malaysian terrestrial should be well-suited to your conditions: it likes shade, high humidity and good air circulation.

Zingiber spectabile [Zingiberaceae - the Ginger family]. Another ginger species, the beehive ginger should not be confused with the related Z. officinale, the
beloved culinary ginger. The plants grow quite tall, with the inflorescences typically carried beneath the attractive foliage. The beehive structure of the flowerhead is - once again - formed from colourful bracts, with the orchid-like flowers themselves appearing from between these. Gardeners and florists have many varieties to choose from, with flowerheads in orange, pink, yellow, red and several bicoloured combinations.

Strongylodon macrobotrys [Fabaceae - the Legume family]. The jade vine produces pendant clusters of totally unique aquamarine flowers. Once you've walked under a pergola festooned with these, the watery blooms of a wisteria seem positively wistful by comparison. It's not only the Orchidaceae that produce flowers of unusual colour, it seems. The jade vine hails from the Philippines, that trove of botanical marvels, where its blooms are visited by rainforest bats. It was first collected in 1854 on Mount Makiling on the island of Luzon by botanists of the U.S. Wilkes Exploring Expedition. Perhaps not surprisingly, it is now exceedingly rare in the wild and faces threat from deforestation.

Catalpa speciosa [Bignoniaceae - the Jacaranda family]. Just as orchids are not confined to the tropics, so orchid mimics can be found in virtually every environment. The Northern catalpa is a deciduous ornamental tree from the United States, orginally found along the Mississippi River basin, but now naturalized throughout much of the Midwest and considered invasive in places. It is known by several names in the vernacular, cigar tree and Indian bean being the most common, refering to the long, slender pods formed in mid-summer after flowering. The showy flowers bring to mind those of a unifoliate Cattleya, being large, white, ruffled and with distinct streaks of colour toward the interior.

Elettaria cardamomum [Zingiberaceae - the Ginger family]. Cardamom is a giant among gingers, growing to a height of almost 4 m. By contrast, the inflorescences are minute and held close to the ground, bearing several small blossoms. It grows wild in moist forests of the Western Ghats on India's Malabar Coast. An expensive spice, cardamom needs to be hand-picked daily at the moment of perfect ripeness. Few gourmands realize that the cardamom they praise so highly for the beauty of its aromatic fragrance has equally beautiful flowers. These blossoms are truly deserving of the moniker 'orchid-like'.

As we have seen, pretty petals do not an orchid make. So what is an orchid, and what isn't? This question can be answered most decisively by genetics. Simply put, an orchid is any member of the family Orchidaceae. Like the New York crime families, it's an exclusive club; they don't allow just anyone in and it doesn't matter if you look the part. However, in lieu of having a full-fledged genetic fingerprinting lab at your disposal the next time you're poking around your favourite nursery, remember that orchids usually exhibit these characteristics:
a prominent lip (labellum) different from the other petals and sepals
resupinate flowers twisted through 180°, leaving the lip lowermost
pollen formed into sticky masses called pollinia
a column (gynostemium) composed of both style and stamen
fruit in the form of dehiscent capsules
very small, almost dust-like seed
close associations with mycorrhizal fungi
And then remember that there are exceptions to almost all those characteristics. Good luck...

Photography credits: Bauhinia blakeana ©
Christoph Diewald; Alpinia zerumbet © Avelino Maestas; Tacca chantrieri © Julia; Zingiber spectabile © Tony; Strongylodon macrobotrys © David Midgley; Catalpa speciosa © Cindy Ware; Elettaria cardamomum © Gopu P. Please visit these exceptional Flickr users for more floral excellence.


Lisa said...

How very interesting! I think the tacca chantrieri looks very much like a rat's face!

Chris Eldin said...

I have catching up to do. I kept clicking in and seeing your ship painting, but now I see I've missed two posts.

I cannot skim your posts, my friend. I need to savor them. Will be back at a more opportune time.

Unknown said...

lisa: somehow, 'rat flower' doesn't carry as much mystique as 'bat flower'.

chriseldin: at least this one is mainly composed of pretty pictures...

Anonymous said...

that black orchid is jaw droppingly pretty!

Lakewood florist

Unknown said...

arlene: erm, none of these plants are actually orchids, I'm afraid. That was the point of the post, you see. For black orchids, go here.

Anonymous said...

A fascinating tour through the intricacies of plant differentiation. Some very striking specimens in there!

Claire said...

Another fine lesson in botanical natural history complete with gorgeous photos. Love it!
Think about maybe writing one entirely about the plants whose bracts are look-alike flowers. I think many people would be surprised by some of these beautiful nonflowers.
As always, well done.

Chris Eldin said...

These are beautiful. You have to have a keen eye (and a PhD!) to tell the difference!

I love cardoman. It's great in tea. And very interesting about the Hong Kong flower. It sounds rather hardy, and again it's most pretty.

The bat flower is my favorite among these. It's stiking.

twanji said...

Pretty Pictures!
Do you still have your o"rchid farm" running in the US?

Shimmerrings said...

I like the one from the ginger family the best... and then the black one, all fancy, with whiskers... plants are amazing... much more amazing than us humans...

*dalyn said...

it's just amazing how many of these beauties fall under the title of 'orchid'. nature is so amazing isn't it? *d

HopSkipJump said...

Orchids or not, I want them in my house! Mind you, they probably do not want to be there. I have an overwhelming urge to hack off all of their silvery-gray roots. I haven't done it yet but my plants are starting to look like giant spiders (Well, Dalyn "accidentally" wrecked one... I'm pretty sure it was on purpose. She gave me a an orchid as a housewarming gift even though she can't seem to grow them. Mine is out of control healthy and she hates me for it).

Wendy said...

Fantastic photo's! The people who took them are really talented. I love the 'bat flower.' I also love your very diplomatic reply to the comment by Theysaywordscanbleed.....

Riss said...

This is the first time I've been by your blog and it's really darn cool. I always read your comments on Lisa's blog and elsewhere and never clicked over to see what your space was like. Really cool stuff.

The Strongylodon macrobotrys...yes I copy pasted the name...has got to be one of the most beautiful things I've seen. I love flowers, I just don't know anything about them. I will definitely be reading more on your blog in the future. (c:

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