Create a garden with a collection of diverse red flowers that will also be bird-friendly. Pauline Deborah R. explains how

When people see red, they are virtually and idiomatically being indignant. But when they ‘really’ see red, it could be in a range of shades as apple red, blood red, cherry red, coral red, crimson red, garnet red, ruby red, scarlet red, strawberry red and wine red. A garden with a collection of diverse red flowers will not only be gorgeous, but also will be bright and bird-friendly.

Garden plants

In many temperate countries, the red flowers that usher surprises in spring are the poppies, tulips, buttercups, azaleas, camellias, foxgloves and lobelias. In Chennai, the more common red-flowered garden plants are the wild sage (Lantana Camara), carnation (Dianthus Chinensis), jungle flame or idli poo (Ixora Coccinea), crown-of thorns (Euphorbia milii), desert rose (Adenium obesum), shoe flower (Hibiscus rosasinensis), Japanese lantern (Hibiscus schizopetalus), football lily (Haemanthus multiflorus), Texas mallow (Malvaviscus arboreus), firecracker jatropha (Jatropha integerrima), balsam (Impatiens balsamina), crimson passion flower (Passiflora vitifolia), fire bush (Hamelia patens) and Scarlet Sage (Salvia splendens). Interestingly, all these species are available in other colours too but the red variety is more popular. Flowers that are commercially popular because of their red colour are the roses, carnations, gerberas and anthuriums. Even few species of the prickly cacti, produce large, bright red flowers.

Sunlight

Sunlight is a mandatory component for all flowering plants because light intensity is important for the development of rich hues. A solo or mix of three major plant pigments chlorophyll, carotenoids and flavonoids in different proportions are responsible for the development of flower colouration. Anthocyanins, an integral component of flavonoids are the major source of red colour in flowers and autumn leaves. Intensive anthocyanins alone will produce dark red flowers, whereas a combination with the yellow carotenoids will make the flower colour slightly tricky to designate, for it could be in shades of red, scarlet, crimson, vermillion, carmine, orangish red, burgundy or maroon. Apart from light intensity, even temperature and soil pH influence flower colour. That’s the reason for gulmohar being more reddish in Bangalore and in hilly terrains while just being vermillion in Chennai.

Flamboyant trees

Most of the red flowers that are produced on trees are quite large, showy and are produced profusely on leafless branches signalling attention to the passerby and also to the pollinators by their conspicuousness.

The most prominent trees that dot the landscape with diverse shades of red blossoms are the Indian coral tree (Erythrina indica), red silk cotton (Bombax malabaricam), gulmohr (Delonix regia), red frangipani (Plumeria rubra), bottle brush (Callistemon citrinus), geiger tree (Cordia sebestena), sand box tree (Hura crepitans), flame of the forest (Butea monosperma), African tulip tree (Spathodea campanulata), rose of Venezuela (Brownea grandiceps) and Rhododendron species.

The three terrific bird-friendly trees in this list are the Indian coral tree, red silk cotton and African tulip tree. These are highly seasonal and start blooming just at the onset of summer, that is sometime in February and stay till April or May. Birds that could be spotted visiting these trees are the different species of sunbirds, spider hunters, flower peckers, parakeets, mynas and orioles.

Pollination

The prominent, red flowers are borne in dense clusters at the canopy of leafless branches, which is an ideal optical advertisement for pollinators. The bird-pollinated flowers are usually odourless and the nectar-feeding birds have a poor sense of smell. These special spectral signatures are exclusively spotted by birds that pollinate the red flowers. Birds have greater spectral sensitivity and finest hue discrimination towards the long wavelength end, which is the red part of spectrum. Since they forage by sight, the garish colours are vital along with the diurnal blooming time and flower clustering at tree tops. The dilute nectar they derive from flowers are rich in sugars and amino acids indicating the fact that it is highly nutritive in nature.

Another reason for the lack of fragrance is that bees take olfactory cues and might invade these flowers for their copious nectar, thereby jeopardising the act of pollination by birds. Few insects, especially bees cannot perceive the red colour clearly and are unable to distinguish between the green leaves and the red flowers and therefore don’t visit red flowers. However certain butterflies navigate through red flowers that have a narrow corolla tube where it can easily thrust its proboscis for procuring nectar. Flowers are under high selection pressure for specific communication channels to attract those who benefit them and ward off those who are nectar robbers and are not pollinators.

The birds that visit red flowers for nectar either showcase a hovering or a perching behaviour. In hovering, birds like sunbirds collect the nectar without landing on the flower. But perching birds land on stems, leaf stalks or branches for adequate support to suck the nectar. During this process, the perching birds might turn aggressive and become destructive. Therefore the flowers require mechanical strengthening and so most of the floral parts of these red flowers are rather cartilaginous in texture.

Urban greening

Though gulmohar is a common tree in Chennai, and displays bright and attractive blooms, it is highly vulnerable to squalls, and is an almost useless tree as it sheds it leaves during summer, failing to provide shade, has nothing to offer for birds and also has a futile timber. Apparently, it is endangered in its native Madagascar, but has carved a prominent niche for itself in our city because of its flamboyant flowers. This species is highly unsuitable for our landscape because of its shallow-roots and minimum eco-utilitarian services.

Being indigenous trees, the coral tree, flame of the forest and red silk cotton make a very good choice for urban avenues and parks for their riotous display of hues during summer that makes the city vibrant and also for being great hosts for birdlife.

The writer is a botanist and assistant professor, department of plant biology, Women's Christian College. Mail her at hinduhabitat@gmail.com.