LOWLAND TROPICS

In the steamy, lush jungles of the Lowland Tropics Gallery, a light rain falls on the canopy of majestic palms. An enormous kapok tree lies on the forest floor while brightly colored orchids and falling water cascade around it. Coffee berries, cacao pods, and tropical fruits hang heavily from branches, and the sweet fragrance of jasmine and Stanhopea orchids mingle in the air. The gallery is also home to the Conservatory’s centenarians, including the towering Imperial Philodendron, a pygmy date palm from San Francisco’s 1915 Panama-Pacific International Exhibition, and 100-year old Cycads, which are primitive gymnosperms that pre-date the dinosaurs.

You can visit all the galleries: Potted Plants | Lowland Tropics | Highland Tropics | Aquatic Plants

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Acalypha hispida
Common Name: Chenille Plant
Family Name: Euphorbiaceae
Native to: New Guinea and the Malay Archipelago

The common name, chenille, means caterpillar in French. The fuzzy, pendulous inflorescence of the chenille plant range in color from vibrant red through a creamy white. The chenille plant is dioecious, meaning the male (staminate) and female (pistillate) flowers are on separate plants. The individual flowers which make up the inflorescence are very tiny, have no petals, and are made up of feathery pistils. These pistils are tightly packed into cylindrical flower clusters along the raceme called catkins. Flowers with catkins, including the chenille, are predominantly pollinated by the wind, and occasionally by insects.

Areca vestiaria
Common Name: Orange Crownshaft Palm
Family Name: Arecaceae
Native to: Eastern Indonesia, Maluku, and Sulawesi

This palm varies from a red crown shaft with maroon leaves, to an orange version with green leaves, and everything in between. It has been observed that there is substantial color variation depending on elevation, with the more colorful plants coming from higher elevations. This photo shows the three stages of the palm’s fruit – the yellow inflorescence emerging, the full-sized but unripe yellow fruit, and the ripe red fruit.

Averrhoa carambola
Common Name: Starfruit
Family Name: Oxalidaceae
Native to: Philippines, Indonesia, Malaysia, India, Bangladesh, and Sri Lanka

Starfruit has distinctive ridges running down its sides (usually five, but can sometimes vary). In cross-section, the fruit resembles a star.

The entire fruit is edible, including the slightly waxy skin. The flesh is crunchy, firm, and extremely juicy. It does not contain fibers and has a texture similar in consistency to that of grapes. They may be used in cooking, and can be made into relishes, preserves, and juice drinks.

Like the grapefruit, starfruit is considered to be a potent inhibitor of some enzymes. Thus, the consumption of carambola or its juice in combination with certain medications can significantly increase their effective dosage within the body. Research into grapefruit juice has identified a number of common medications affected, including statins, which are commonly used to treat cardiovascular illness.

Carica papaya
Common Name: Papaya
Family Name: Caricaceae
Native to: Tropical America 

The papaya is commonly referred to as a tree, but it is technically a giant herb because it never produces true woody tissue.

The papaya typically has a single, unbranched, non-woody trunk. The trunk is topped by an umbrella-like canopy of palmately lobed leaves. The stems and leaves contain white milky latex. Papayas are dioecious with male and female flowers on separate plants, but many cultivars are hermaphroditic. Their yellowish-white trumpet-shaped flowers are fragrant and bloom throughout the year.

The papaya is used all over the world in traditional medicine for its digestive, wound-healing, and anthelmintic properties. These properties originate from the presence of the enzyme papain in the latex of the papaya plant and its fruit.

Coffea arabica
Common Name: Coffee
Family Name: Rubiaceae
Native to: Ethiopia

Coffea arabica and Coffea canephora are the two major commercially grown species of coffee. Coffea arabica is said to produce better tasting coffee because the lower caffeine content makes it less bitter.

Scientists have determined a number of ways coffee plants use caffeine to their benefit. When leaves die and decompose on the ground they contaminate the soil with caffeine which makes it difficult for other plants to grow. Coffee plants also use caffeine to deter insects from eating their young leaves and beans. With the high doses of caffeine contained in these plant parts, a bite can be fatal to insects. But the nectar contained in coffee flowers is laced with a small dose of caffeine. When insects feed on caffeine-spiked nectar, they are more likely to remember the flower and revisit it again, which aids in pollen dispersal.

Crescentia cujete
Common Name: Calabash Tree
Family Name: Bignoniaceae
Native to: Central and South America

Crescentia cujete, more commonly known as the calabash tree, has been cultivated throughout tropical Central and South America since prehistoric times. The light green bell-shaped flowers grow directly on the trunk and branches and are pollinated by bats. The fruit is botanically a berry and widely utilized to make bowls, jugs, utensils, and musical instruments.

Dioon spinulosum
Common Name: Giant Dioon
Family Name: Zamiaceae
Native to: Veracruz and Oaxaca, Mexico

Cycads are a unique, ancient lineage of plants that flourished in the Mesozoic Era approximately 250 million years ago. Commonly mistaken as a palm or fern, the cycad is in fact not closely related to either. This particular cycad is over 100 years old.

Dioon spinulosum is one of the tallest cycad species in the world, growing to 40 feet high.  A cycad is either male or female and the cones of each sex are usually quite different in size and shape.  When the female cones ripen and open they will reveal hundreds of orange, unfertilized ovules. For the cone’s ovules to be fertilized, the Conservatory would need pollen from a male plant of the same species, which we do not have at the Conservatory. So, this giant Dioon will repeat it’s cycle of producing unfertilized cones, year after year, without producing offspring. Fortunately, cycads can also produce stem offshoots, often called pups. These can be separated from the parent and rooted to create new plants.

Epiphyllum
Common Name: Orchid Cacti
Family Name: Cactaceae
Native to: Central America

This impressive bloom is the flower of an Epiphyllum cactus. There are 19 species of cacti in this genus. They are epiphytic and will usually root in small amounts of moss or debris that collect on branches. The blooms are large and usually quite fragrant. Some species have edible fruit.

Hibiscus schizopetalus
Common Name: Japanese Lantern, Spider Hibiscus
Family Name: Malvaceae
Native to: Kenya, Tanzania, and Mozambique

The red or pink flowers of this Hibiscus are distinctive in their frilly, finely divided petals that curve up and create a globe shape. A long reproductive column protrudes from the center of the petals. The column is covered with stamens, the part of the flower that produces pollen. At the tip of the column are stigmas, where pollen lands and starts the fertilization process.

Medinilla
Family Name: Melastomataceae
Native to: Africa, Madagascar, Asia, and Pacific Islands

Medinilla is a genus of about 150 species in the family Melastomataceae. Most species are evergreen shrubs with white, pink, or orange flowers. The flowers are arranged on a panicle, a branched cluster of flowers. When pollinated, the plant bears showy berries. The leaves of many Medinilla species are arranged in a whorl or are alternating. This allows the maximum amount of sunlight to hit each leaf.

 The genus Medinilla was named in 1820 after J. de Medinilla, governor of the Mariana Islands, which are off the coast of the Philippines. There are more than 100 endemic species of Medinilla in the Philippines alone.

Musa
Common Name: Banana
Family Name: Musaceae
Native to: Southeast Asia and Australia

In horticulture, parthenocarpy (which literally means “virgin fruit”) is the natural or artificially induced production of fruit without fertilization of ovules. The fruit is therefore seedless. Seedlessness is seen as a desirable trait in edible fruit with hard seeds such as watermelon, clementines, grapes, and grapefruit. Bananas are another example of parthenocarpy, which explains how the Conservatory’s plantains and banana plants can bear fruit without a pollinator being present. The common banana is triploid, meaning it has three sets of chromosomes. Triploids cannot produce a functional seed, but they still develop good fruit through parthenocarpy. After the stalk has flowered and borne fruit, it dies.

So how does a banana plant reproduce? There are side shoots or suckers at the base of the main stalk, which can be removed and replanted.  Banana flowers are protected by bracts. The bracts fold away one-by-one and reveal hundreds of flowers. Female flowers appear first and develop into hands of fruit. The male flowers emerge last and do not become fruit. In Southeast Asia the male flowers are boiled and eaten as a vegetable. Bananas are cultivated in 135 tropical and subtropical countries.

Petrea volubilis
Common Name: Sandpaper Vine, Queen's Wreath
Family Name: Verbenaceae
Native to: Central America and Lesser Antilles

Petrea is a genus of evergreen flowering vines. They have rough-textured leaves, hence the common name sandpaper vine. Dangling from the raceme (hanging cluster of flowers) are dozens of pale purple sepals. Violet flowers grow from the center of the sepals. The sepals serve to attract pollinators to the smaller flower. The flower only lasts a few days but the sepals remain for weeks.

Phoenix roebelenii
Common Name: Pygmy Date Palm
Family Name: Arecaceae
Native to: Southeast Asia

The Conservatory’s pygmy date palm is a prized relic from the Panama-Pacific International Exposition. The Expo was held over 100 years ago in 1915. This elegant arching palm was donated to the Conservatory after the closing of the exposition. Each pinnate leaf, or frond, has 100 narrow, shiny leaflets. When in bloom, it drops hundreds of tiny white flowers that blanket the ground of the gallery. 

In 1889 James O’Brien, one of the most famous horticulturists of the 19th century, named the palm “roebelenii” in honor of the German orchid collector Carl Roebelen who was the first to completely document the plant in Laos. The pygmy date palm quickly became popular in landscapes and collections for its attractive leaves and trunk. By 1915, this palm would have been a common hot house plant.

Psidium cattleianum
Common Name: Strawberry Guava
Family Name: Myrtaceae
Native to: Brazil

Psidium cattleianum is a small tropical evergreen tree that in the same family as the common guava, Psidium guajava. The fleshy fruit of the strawberry guava turn purple or red as the fruit matures; some varieties of Psidium cattleianum have yellow fruit. The fruit is edible and juicy with a strawberry-like flavor. The upper surface of the leaves is dark green and glossy, while the lower surface is whitish green in color and punctuated with small oil cavities that give it aromatic qualities.

Strawberry guava is native to the coastal areas of eastern Brazil, where it is known as “araçá”. However, the tree quickly adapts to a variety of climates and is considered an invasive weed in many tropical areas, particularly Hawaii and the Caribbean islands. The strawberry guava was brought to Hawaii in 1825 for its fruit and ornamental attributes; however, it now threatens Hawaii’s native forests. The strawberry guava grows in monotypic stands that displace native tree species. Psidium cattleianum quickly spreads both by shoots and seeds, with the help of non-native birds and pigs that consume the fruit and spread the seeds to new areas. Restoration efforts are underway in Hawaii to control the growth of P. cattleianum and restore native forest species.

Tabernaemontana divaricata
Common Name: Pinwheelflower
Family Name: Apocynaceae
Native to: India

Tabernaemontana divaricata, commonly known as the pinwheelflower, is native to India and cultivated throughout South East Asia. This small evergreen shrub grows to approximately 5-6 feet tall and the waxy, deep green leaves grow to 6 inches in length. The white, five-petaled pinwheel flowers bloom in small clusters on the stem tips. When broken, the stems exude a milky latex that is toxic. However, in prescribed quantities, parts of the plant are used to treat a variety of ailments ranging from hypertension, headaches, to scabies. Ecologically, Tabernaemontana divaricata is a host plant for the caterpillars of the oleander hawk-moth (Daphnis nerii).

Verschaffeltia splendida
Common Name: Seychelles Stilt Palm
Family Name: Arecaceae
Native to: Seychelles

Verschaffeltia splendida is only found on three islands in the Seychelles where it is threatened by habitat loss. This canopy or understory palm grows in moist rainforests on steep hillsides and ledges. The stilt root system is thought to have evolved to stabilize the palm on steep slopes and in strong winds. The spikes on the trunk of the palm protect it from hungry animals.

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Golden Gate Park | 100 John F. Kennedy Drive | San Francisco, CA 94118| 415-831-2090