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Perfect Disguises

Green Country Vol. 112 (Feb 2015)

Flowers, with their wonderful variety of colours and forms, are the most conspicuous, charming parts of plants. In fact, more colourful and larger flowers are more attractive to insects, so increasing the chance of pollination. However, not all plants have beautiful flowers. They rely on other ways to attract insects, such as having leaves or other parts that resemble petals and corolla to confuse pollinators!

Bract

Bracts are specially evolved leaves that are usually located under the flowers. They differ from common leaves in shape, size, colour, texture and even function. The unique bracts are often mistaken as being part of the flowers. The winter blooming Poinsettia (Euphorbia pulcherrima) is the most familiar example. The large red “Christmas flowers” are in fact bracts, while the real flowers are very tiny and lack fragrance. The trick of turning part of the leaves into bright red bracts does the work of attracting pollinators towards the small flowers!

Another species with attractive bracts is Brazil Bougainvillea (Bougainvillea spectabilis). Not only are the bracts brightly coloured, but they are elegantly shaped. In early spring, peach red flowers blossom and grace hillsides and parks. In reality, the peach red parts are the bracts, which embrace the genuine flowers that look like stamens. The bracts of Brazil Bougainvillea are attractive to insects as well as for people. The plants are often used in decorating walkways, walls and fences, or as pot plants.

Calyx / Sepals

Calyx grows at the outside of flowers. In general, calyx is green and relatively hard, making it more resistant to insect attack and protecting flower buds before they bloom. However, the protectors sometimes take up a more eye-catching role.

Buddha's Lamp (Mussaenda pubescens) has tiny flowers. Its calyx helps to dress it up with large, snow white “flowers”. Each flower has five sepals, four of which are small and slender while the remaining one is enlarged into a petal-shape and turns from green to white. These enlarged sepals form a “flower” as clusters of the real ones grow together.

The calyx of Bleeding Hearts (Clerodendrum thomsonae) transform themselves to become big white lanterns, on top of the bright red corolla and long pistils, creating an enchanting natural portrait!

Stamen

Some plants deploy their petal-like stamens to confuse pollinators. Ginger Lily (Hedychium coronarium) is one example. The white, aromatic “flowers” that are evolved from stamens resemble butterflies. But where are the real petals? They are hiding behind – the three slender parts are the real ones! The evolved petals have no pollen. Only those stamens that are not evolved combine with the style and stigma of pistils to form a special club-shaped reproductive structure.

Shell Ginger (Alpinia zerumbet),a relative of Ginger Lily, bear flowers of brightly coloured flowers. The largest “petals”—evolved from stamen as well—are lip-shaped, red and yellow. The spacious area allows insects to fly down and stop for pollination. The real and plain petal is white with little red, on the other hand, and sits on the upper side of the lip-shaped fake “petal”!

Text|Helen Yau

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The “red flowers” of Poinsettia are in fact bracts.
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The central milky white part is the real flower of Brazil Bougainvillea.
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“Sea of flowers” of Brazil Bougainvillea.
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The large, white "flowers” of Buddha's Lamp are in fact sepals.
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Bleeding Hearts have unique and graceful calyx.
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Some stamens of Ginger Lily have evolved into butterfly-like “petals”.
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The red “petal” of Shell Ginger is transformed from stamen.

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