Costus spectabilis: 'Massonia' of tropical Africa

Tim Chapman
Sat, 29 May 2010 10:27:33 PDT
Just a little background on this species:  most if not all of these  
grown in the US are divisions of plants I introduced about 17 years  
ago ( my plants came from Kew, don't have the original collection data).

I didn't have much luck with it in the ground here (zone 8 Louisiana),  
but it's easy enough in pots. Part of the reason it's not very common  
in the trade is that the rhizomes break easily when shipped. Even  
repotting a plant can lead to the main plant breaking away from the  
rhizome.  I'm sure a better method could be developed but tissue  
culture using the standard Ginger method led to several test tubes of  
rhizomes! Never a leaf or root!!

Even in a three gallon pot the rhizome will reach the bottom then grow  
in a circle around the pot.

Commercially it would probably be best sold as dormant rhizomes.

The flowers are among the largest of the costaceae, and certainly one  
of the most beautiful.

I've seen some slides taken in Gabon of a very similar species  
( unknown) that has the same foliage habit but has a 1-2 foot  

Tim Chapman

On May 28, 2010, at 10:25 PM, Jacob Knecht <>  

> Dear Members,
> Two days ago our *Costus spectabilis* bloomed for the first time.   
> What an
> exciting event!  The flower is ephemeral lasting only one day, but  
> the plant
> is a sequential bloomer.
> Most gingers and other zingiberales technically meet the Pacific Bulb
> Society criteria for what constitutes a geophyte, but this species  
> is rather
> unique for its genus and fits even the most stringent qualifications  
> for
> this category.  It goes completely dormant during the dry winter,  
> retreating
> back to a centipede-like rhizome that lacks perennial roots.  Unlike  
> other *
> Costus*, this acaulescent species doesn't form aboveground stems.   
> After a
> dry winter rest, the combination of warmth and water in late spring  
> cause it
> to pierce through the bare ground, opening beautiful rosettes of round
> paddle leaves that will appress themselves to the soil once fully  
> formed.
> The plants are somewhat reminiscent of *Massonia* or lily pads  
> floating on
> the surface of the earth.  New leaves have an attractive golden  
> sheen, and
> many clones have gorgeous red ciliate leaf margins.  The abaxial leaf
> surface consists of a spongy white texture, akin to styrofoam.
> The flowers are brilliant yellow, sort of resembling a squash  
> blossom, 9cm
> wide.  When it fades, it also resembles a squash blossom!  The  
> petals are
> not very conspicuous, however the real showy part of the flower is  
> the large
> staminodial labellum.  The texture is so soft and thin, with a crisped
> margin. Perhaps the most delightful floral detail is that it  
> sparkles in
> sunlight!  This rhizomatous geophyte is native to much of tropical  
> Africa:
> Benin, Burkina Faso, Côte d'Ivoire, Ghana, Guinea, Mali, Nigeria, Se 
> negal,
> Sierra Leone, Togo, Burundi, Cameroon, Gabon, DRC, Chad, Ethiopia,  
> Sudan,
> Kenya, Tanzania, Uganda, Angola, Malawi, Zambia, and Zimbabwe.   
> Surprisingly
> it is rare in cultivation, at least outside of the African continent.
> When grown in a pot, as shown in my pictures, the curious centipede- 
> shaped
> rhizomes circle the pot causing the rosettes of leaves to grow crowded
> together instead of spreading out.  Last year I grew it outdoors in  
> Upper
> Mānoa Valley (O'ahu, Hawai'i), a wet montane tropical environment.   
> It grew
> well but did not bloom.  I suspect that this was due to a lack of  
> strong
> sunlight and heat  (other heat-loving geophytes also failed to bloom  
> in this
> situation i.e. *Bessera elegans*, *Milla magnifica*). This year I  
> placed it
> under a sodium halide light in my indoor orchid vivarium.  It  
> received high
> light (5500fc), 14-hour days, high humidity, air movement, daytime  
> temp
> 27°C, night-time temp 20°C.  I moved it out to enjoy the bloom and i 
> n the
> past few days the leaves have surprisingly raised themselves into a  
> more
> diagonal orientation.  I think this may be a response to lower light
> intensity.
> This is a promising horticultural subject for climates with warm humid
> summers.  Certainly this would be a wonderful garden plant in  
> seasonally dry
> tropical lowlands such as leeward/Kona Hawai'i, extreme S Florida,  
> much of S
> and SE Asia, Queensland, India, Caribbean, Meso- and S America and  
> Africa.
> It is not hardy outdoors in S California. It should be kept dry in  
> dormancy,
> so folks in climates with non-tropical winters can simply bring the  
> pots
> indoors and keep them dry on a shelf or in a box until the following
> spring.  Shallow wide bulb pans are best.  I suspect this would grow  
> well as
> a potted tender perennial in the US South and East Coast.
> Selected pictures of our plant:
> *
> In situ* pictures:
> Enjoy!
> Jacob Uluwehi Knecht
> ----------
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