Red Button Spiral Ginger

**Red Button Spiral Ginger (Costus woodsonii)**

Multiple locations, including Bayfront Shuttle Bay and Supertree Grove

A common sight around the parks and gardens of Singapore, the red button spiral ginger (Costus woodsonii) is actually a New World native, from the forests of continental Central America to Colombia. While it may only reach a metre in height, this skinny, succulent plant makes up in character what it lacks in height! A distant relative of the true gingers, it is in the ginger and banana order (Zingiberales), but a member of the spiral ginger (Costaceae) family, named for its gently spiraling stems.

This particularly tall stalk of red button spiral ginger shows the gentle, spiralling curves of the stem that give the spiral gingers their name!

There are about 100 different species in the Costus genus and the red button spiral ginger is one of the showiest. Its long, pine-cone-like flower stalks (inflorescences) sport a spiralling series of deep red scale-like modified leaves called bracts. From within each scale-like bract, a bright orange-red tubular flower grows out and eventually opens slightly to reveal a yellow-orange lip.

From within each of the scales of the red, pine-cone like inflorescence, a tubular flower will grow out. Usually, one to three flowers will be open on a flower stalk at a time. Resting on a leaf in the foreground is a plucked flower, showing the white base where the nectary is. Can you find the tiny drop of nectar that has spilled onto the leaf?

All kinds of animals are attracted to the sugary sweet nectar produced by the plant, both at the inner base of each flower and at extrafloral nectaries between the bracts. Some are protectors, some pollinators, and others, plunderers! In their native range across Central and South America, the red button spiral ginger is pollinated by hummingbirds which stick their long curved beaks and mobile tongues deep into the mouth of the flower to slurp up the nectar at the base, picking up and transferring pollen in the process.

This spiral ginger has also developed extrafloral nectaries outside of the flower to facilitate an interesting symbiotic relationship with a particular species of ant that helps protect the flower clusters warding off a particular species of fly that tries to deposit its eggs on the inflorescences. If not protected by the ants, the fly larvae eventually would burrow into the flower stalk and eat the developing seeds and fleshy arils, thus hampering the plant’s reproductive capacity.

Ants (left) and bees (right) swarm around the inflorescences, probing for nectar at the extrafloral nectaries that are outside of the flowers, in-between the scaly bracts

There are no hummingbirds in Singapore, but their tropical Asian equivalent are the sunbirds – a family of small, slender, often brightly-coloured, nectar-drinking birds. Unlike hummingbirds which can hover in front of the flowers to still their bills in the outward facing mouth, sunbirds can’t hover so well and must stand and perch to feed. So, the cheeky sunbirds have developed a stand-and-stab method, perching on top of the inflorescence and stabbing their bills directly into the upward facing base of the flowers for easy access to the nectar. Because this method bypasses the floral tube (corolla) where the anthers and stigma are, instead of pollinating the flower, the sunbirds just plunder their nectar!

Sunbirds, like the garden sunbird (Cinnyris jugularis, left) steal nectar by stabbing its beak directly through the upward facing base of each flower, bypassing the flower’s reproductive parts to sip the nectar directly at the base, tearing big holes into flowers (right).

Bees, birds, and ants aren’t the only ones who find the nectar of the red button spiral ginger irresistible! The entire flower is also edible for humans. Whole, blooming flowers can be plucked right out of the inflorescence and crunched on raw (please do not pluck any plants or flowers in the Gardens or any public plantings in Singapore!). The sweetness from the nectar is balanced by a sour tang from the oxalic acid also present in the flowers, for a texture and taste reminiscent of green apples or green grapes!

These look a bit like a red torch ginger (Etlingera elatior) but they are actually cristate or crested inflorescences of the red button spiral ginger, formed by spontaneous mutation.

Cockscomb (Celosia argentea var. cristata) isn’t the only red crested plant around; the red button spiral ginger can occasionally have crested inflorescences as well! Caused by spontaneous mutations that affect cell division, a few of these rarely-seen, unstable, flower heads can be seen at bed of red button spiral ginger right near the Bayfront shuttle stop! Come and admire them from afar while they last and you may even be rewarded with photos of sunbirds stealing nectar from their flowers!

Want to find out more about the delicious spiral ginger flowers and other edible plants in Gardens by the Bay? Click the link below to find out more about our free, weekend guided walking tour - A Sensory Stroll - Can Eat or Not? and other exciting tours in our Nature and Sustainability tour series!

Written by: Janelle Jung, Senior Researcher (Research and Horticulture)

A transplanted pake (Hawai'i-born Chinese), she's finding her own Singaporean roots. Every plant has a story, and Janelle helps discover and share these with colleagues and guests, hoping to spark a mutual plant passion! Ask her what plant she named her cat after!