TROPICAL NIGHT BLOOMING PLANTS

by Larry M. Schokman

Director Emeritus

The Kampong of the National Tropical Botanical Garden

As you enter a tropical garden at night you may soon be aware of a subtle and sometimes over-powering fragrance. Since most of the flowers close after sunset, there must be a different source of perfume.  As flowering night blooming trees, shrubs and herbs begin to open, the air is permeated by their fragrance, which in turn adds a hint of romance to the evening.

 It may be a surprise to some human visitors that a tropical garden at night may be as active and alive as it is in mid-morning. Nocturnally active hawkmoths and bats replace the diurnally active bees, birds and butterflies as pollinators and/or predators. Plants too are specialized in the symbiosis of flower display and pollinators.

 At The Kampong we are aware that as some plants mature and open their flowers, they become sexually active in the evening, at night or before dawn. Plants that bloom at night are called crepuscular bloomers. Some of them produce a pleasing aroma, and others a disagreeable or even foetid odor, but most of them produce an abundance of nectar from special glands in the flower that attract bats or moths. The sources of pleasant perfume are usually found in tubular-shaped flowers that are white or light yellow in color. Long-tongued hawkmoths visit these flowers, in their quest for nectar. Flowers that are dark red-brown in color (that resembles decaying flesh) usually have a foetid odor (e.g., Sterculia foetida, and Amorphophallus). Fragrance is as important as color and flower form in a garden.  Unfortunately, in our desire to develop bigger and brighter colored flowers, it is usually at the expense of fragrance.  What aesthetic satisfaction is there if a large, perfectly shaped rose, with splendid color, has no perfume?  Bees, like some humans, are color blind to the red part of the spectrum. So on that premise, a magnificent red rose, without a trace of perfume, is doomed to remain unpollinated!

 The common white ginger Hedychium coronarium, which is worn as a corsage flower in the Caribbean and used for leis in Hawaii, exudes a fragrance all evening. Its Spanish name is “dama de noche,” which translates into “queen of the night.”

 The herbaceous tobacco plants in the family Solanaceae are extremely fragrant, e.g., Nicotiana x sanderae (and sometimes a little hallucinogenic too! (e.g., Brugmansia and Datura). As the scientific name implies, Cestrum nocturnum makes its presence known by flowering aromatically at night.

 Common names also reflect this activity; e.g., “night blooming cactus” (Hylocereus undatus and Selenicereus grandiflorus), “lady of the night” (Brunfelsia americana) and “night-jasmine” (Nyctantes arbor - tristes). These plants deserve a place in a tropical garden , for their fragrance as well as their aesthetic charm.

 Most of the night-blooming trees are confined to three families—Bignoniaceae (trumpet family), Bombacaceae (Kapok family) and Mimosaceae (pea or legume family). They are usually pollinated by bats in their native habitat, but in the urbanized areas of South Florida, we have few or no bats to perform this important aspect of fertilization.

 Bat pollinated flowers are usually larger, have more nectar, and some have a musty odor. Bats roost during the day and forage at night, and in the process pollinate many flowers and also scavenge for rotten fruit. Their contribution to the environment (and to humans) is often misunderstood. They vary in size with wing spans of a few inches to three or four feet (“flying foxes” in the tropics) and are often killed indiscriminately because they are incorrectly considered as blood-sucking vampires, eaten as delicacies, or used in some cultures for ayurvedic medicine. A single brown bat can eat up to 600 mosquitoes an hour. Unfortunately, nearly 40% of American bat species are endangered because they are losing their habitat, and are the slowest reproducing mammals (for their size) on this planet—only one baby bat per year.

BIGNONIACEAE

 Kigelia africana (formerly pinnata)—Sausage tree—native to tropical Africa, produces 18-inch long “sausages,” which contain the seeds. Local trees have to be hand-pollinated (because they are self-incompatible) with pollen from other trees. Sometimes birds (spot-breasted orioles, introduced from Mexico) inadvertently pollinate these fascinating claret-colored inflorescences, which have a lot of nectar. Flowers open at dusk and remain receptive till a little after sunrise. They are shaped to accommodate the head of a fruitbat. As it drinks the nectar, pollen attaches to its nose, and is carried to the next flower which is then pollinated.

 Oroxylum indicum—Midnight Horror or Sword of Damocles, from Asia—because the pod can be  almost three feet long and literally hangs on what appears to be a thread! It is mainly a horticultural curiosity. Flowers are similar to K. pinnata, but smaller and greenish/yellow. Also bat pollinated.

 Since bats cannot hover, as do hummingbirds, the flowers they visit must be sturdy enough to support their weight, or be located near a portion of the plant that it can grasp. Bats also prefer not to fly in dense vegetation. The long and sturdy flower stalks of Oroxylum are erect, while those of  Kigelia are pendant. Both encourage bat pollination. The adaptations to display of flowers and pollinators in this family is very interesting.

 Crescentia cujete—Calabash tree—smooth, hard-shelled gourds used for carrying and storing water in its native tropical America, the West Indies, Africa and Southeast Asia (i.e., before the advent of plastic containers!). Flowers and subsequent fruits (up to 2 feet in diameter) are cauliflorus.

 Dendrosicus latifolius—Black calabash—used as “maracas,” the popular dance rattle in the Caribbean, and a popular tourist purchase in Mexico.

 Parmentiera aculeata—Guajilote—fruits cauliflorous, edible, but fibrous. Another curious fruit which is sold in markets in Central and South America. The flowers, like those of P. cerifera are small and greenish/yellow.

 Parmentiera cerifera—Candle tree—creamy yellow cauliflorous fruit, resembling candles. We have both these species grafted on one tree at The Kampong.

BOMBACACEAE

 The name “Bombax” is Greek for raw silk, because of the delicate cottony fluff in many of the seed pods. This family is noted for the massive trunks and large buttress roots of the species Adansonia, Bombax and Ceiba. Many have large showy clusters of stamens produced in buds that open explosively. These clusters of stamens break free from the flower after a short time, and litter the ground, giving it an extra dimension of beauty.

 Fruits vary in size with Kigelia africana (Sausage) being the largest in South Florida and the Caribbean, followed closely by Adansonia digitata (Baobab) and Pachira aquatica (Guinea chestnut). Some genera produce fruit with copious hairs developed from the wall of the fruit which surround the seeds (Ceiba and Pseudobombax), while in others the seeds are large and edible (Pachira) or enclosed in a spongy mass.

 Many of these genera produce their flowers while the tree is in a leafless condition. The Tropical Flowering Tree Society is observing cultivars that emphasize this phenomenon, which accentuates the aesthetics of flowering. Cultivars which are more attractive and prolific in flower will be a-sexually propagated and distributed to our members and local community (at nominal cost) through raffles at our monthly meetings, and at our annual plant sale on Mother’s Day in May.

 Pseudobombax ellipticum—Shaving brush tree—pods “pop” open at dusk. Flowers resemble a shaving brush. Tree is leafless when in flower. The late Mrs. Alvin (Nell) Jennings used these unopened flowers as a floral arrangement at dinner parties. During the course of dinner, these finger-shaped buds would pop open to the surprise and delight of her guests.

 Ceiba pentandra—Kapok—Pink or whitish-yellow flowers with 1 inch petals, bloom in winter. Huge buttress roots stabilize the base of this massive tree. The cotton-like material in the pods is used for stuffing mattresses and pillows in Southeast Asia.

 Ceiba acuminata—Pochote—off-white or pinkish creamy flowers up to six inches in diameter, from Mexico. Thorny. Faintly aromatic.

 Bombax ceiba (a.k.a. Bombax malabaricum)—large red “silk cotton” tree from India. The fleshy calyx of the large lily-like fallen flowers is sometimes eaten in Southeast Asia. Prolific winter bloomer, usually before emergence of leaves. Some trees bloom with leaves on tree, while others are totally leafless. Colors vary from iridescent red to orange/red and even yellow. There are a number of these trees all over South Florida, and despite seedling variation, all of them spectacular, especially when they flower.

 Chorisia insignis—sometimes called the “yellow flowered” Chorisia. They also flower in a white form. Thorny trunk. Native of Peru and Northeast Argentina.

 Chorisia speciosa (Ceiba speciosa?)—Floss silk tree. Fast-growing, large, thorny (sometimes not) tree, which has flowered from seed in less than 4 years in Miami. Some trees flower when totally leafless, accentuating their splendor in Fall or Summer. Several inter-generic (i.e., Chorisia speciosa cv. “Sugar-loaf” x Bombax rhodognaphalon) hybrids from The Kampong are now flowering all over Miami, and the different color combinations, size and shape of the new flowers are exciting to behold. Once established, they require little attention, and like most flowering trees, are ideal candidates for the xeriscape garden. Native of southern Brazil and Argentina.

Pachira aquatica—Guinea chestnut, native in the West Indies. The attractiveness of the large flowers is due to conspicuous white stamens. Medium-sized tree. Native of tropical South America.

 Adansonia digitata—the famous Baobab or “upside-down” tree from tropical Africa (a.k.a. Judas fruit, because it has 30 seeds). We have used the spongy acid pulp as a substitute for Parmesan cheese on pasta—no cholesterol! It is facetiously called the “Dead Rat” tree because its furry fruits resemble rats strung up by their tails(!), and is one of the largest and longest lived trees in the world.

  Durio zibethinus—Durian—very popular fruit in Southeast Asia, which is considered to be an aphrodisiac! An acquired taste—people usually love it or hate it! The arils of this malodorous fruit taste of vanilla, caramel and bananas, with a pervasive onion and sulfur flavor. It is the oil from the edible portion of the fruit (i.e., the aril around the seed) that produces the noxious (to some!) aroma. It is cauliflorous in some species and is probably pollinated by bats. Dr. Fairchild describes it, “The Durian is the most remarkable fruit in the world. The head-hunters of Borneo will commit murder to possess it.”  It has not flowered in South Florida.

 Cavanillessia platanifolia—Quipo. Large tree with smooth pale brown trunk. Soft wood like balsa. Flowers have five red petals less than an inch long. Only a few trees in South Florida. Native of Colombia and Panama.

  Ochroma pyramidale—Balsa or Corkwood. Large, fast growing tree. Large flowers develop at branch tips, with yellowish or brownish-white petals. Native of tropical America. It proved to be a weed tree when it invaded the old bauxite pits in Jamaica.

MIMOSACEAE

  Calliandra haematocephala (red or white powderpuff) is aptly named. From the Greek ‘kallos’ (beauty) and ‘andros’ (stamens), for their beautiful clusters of flowers with 3" long stamens, devoid of petals.

  Parkia speciosa—balls of flowers hang at the end of 12-24 inch pendulous stems (called peduncles)  Flowers are bat pollinated in their native areas, and last but one night. Leaflets are like small feathered twigs.

  Mimosoid legumes are similar to Parkia, e.g., Albizia, Pithecellobium, Samanea and  Wallaceodendron. The ground beneath these trees is littered each morning with masses of stamen-clusters shed from flowers that opened at night.

CAPPARIDACEAE

 Capparis spinosa—caper tree. Capers are pickles made by preserving the flower buds of this spiny shrub. You need to get up early to observe species of Capparis at their peak display.

 Crateva tapia—garlic pear. Named after Cratevas, an obscure writer on medicinal plants. The specimen at The Kampong flowers all winter long.

ANNONACEAE

 Cananga odorata—Ylang ylang—pale yellow flowers year round and the strongest perfume is in early morning and evening. Used to be source of Chanel #5 perfume and Cananga hair oil. Flowers open day and night during most of the year. Perfume is distilled from the reddish-orange glandular hairs at the base of the three petals. Commercially, flowers are gathered early in the morning, before the sun rays dry up the glandular hairs and dissipate their aroma. Stamens are small (not showy) and blackish, olive-sized fruits are not edible, unlike many others in this family (e.g., sweetsop, soursop, atemoya, cherimoya).

BARRINGTONIACEAE

 Barringtonia asiatica, formerly B. speciosa—large white flowers consisting chiefly of a group of numerous long white stamens. Large to medium sized, magnolia-like tree. Leaves clustered at branch ends are 6-18" long. Fragrant white flowers clustered at branch ends, open in the evening and fall in the morning. The yellow-brown heart-shaped fruit is about 4" long, contains one seed, which is poisonous. The husk (like coconut) is fibrous and buoyant which enables the seed to float long distances in the ocean.

Natives of Tahiti claim that Barringtonia sprang from the heart (i.e. because of the heart-shaped fruit) and call the tree “hutu,” which means “heart.” It is also called the “Bishop’s miter,” because of its three-sided fruit.  It is salt tolerant, and has flowered in South Florida, even though it is not too cold tolerant.

 RUTACEAE

 Murraya paniculata—Orange Jessamine. Highly scented flowers used for garlands in Southeast Asia. A large shrub or small tree, which flowers several times during the year. The flowers remain open and attractive during the day, but offer a heady perfume, primarily in the evening, at night and early morning.

Most of us enjoy the beauty and perfume of these night-blooming trees (even in daylight), but for the more curious and observant, we have evidence of sexual activity at night. So here is a special project waiting for the inquiring mind of an investigator...