Commelinaceae through Nyctaginaceae
This family of herbs is often succulent and frequently has cymose flowers, which sometimes have a boat-shaped spathe. The simple leaves are alternate, parallel veined and usually have a closed sheathing base. The flowers are bisexual and actinomorphic or zygomorphic. The fruit is a loculicidal capsule or indehiscent. Species include the Dichorisandra thysiflora, or blue ginger, Tradescantia virginiana, or spiderwort, and Zebrina pendula, or the wandering Jew.
These plants are woody, un-branched or sparsely branched, palm-like, dioecious trees or shrubs. Although cycads look like a cross between palms and ferns they are more closely related to conifers. The cones can be yellow, scarlet, maroon, orange, or apricot and are not produced every year by the female because the process takes an enormous amount of energy. Heat is generated by the cones to attract weevils, which help pollinate. A species in Indonesia have cones that smell so bad that locals chop them down and bury them. Leaves are compound, alternate, and spirally arranged to cluster at the stem. The leaves are also frond-like, stiff and typically have a single mid-vein. The seeds, stems, and leaves of many cycads contain a neurotoxin potent enough to paralyze cattle or cause Alzheimer’s-like effects in humans. This family is found in tropical and subtropical areas. A few species are in Costa Rica and are very common in the fire climax woodlands of Australia.
Cycas revolute........................................Cycas circinalis
Euphorbiaceae are mostly paleotropical. They can be monoecious or dioecious. The flowers are actinomorphic. The fruit is usually a capsular schizocarp, which is a fruit that splits at maturity into two or more closed one-seeded parts. Euphorbiaceae are herbs, shrubs, and trees. Many are cactus-like but with weaker spines and have a poisonous milky sap. This family is one of the largest including 7,500 species. Some can bear leaves that are simple or compound when well watered. Most have alternate leaves but a few are opposite or whorled. The plant Manihot esculenta is a shrub from Brazil that is widely cultivated in the tropics for its roots provide a good source of starch. Another plant in this family is Euphorbia splendens, also known as Euphorbia millii, an ornamental shrub from Madagascar that legend says had white bracts until the plant was worn as a “crown of thorns” by Christ, turning the bracts red.
Euphorbia baivensis............................Euphorbia tirucalli...............................Euphorbia milii
Euphorbia canariensis (foreground) with Euphorbia trigona (background and close-up, right)
Legumes are a significant component of nearly all terrestrial biomes and comprise one of the largest families of flowering plants. Species range from dwarf herbs of arctic and alpine vegetation to massive trees of tropical forests. Common species that are seen all over campus are the Bird’s Foot Trefoil and the White Clover. The unifying characteristic of the family is the fruit, a pod, known as the Legume. It is designed to encourage dispersal by animals, wind, and water. Leaves are typically pinnately compound. Many Legumes convert atmospheric nitrogen into nitrogenous compounds useful to plants. This is accomplished by the presence of root nodules, which contain the bacteria of the genus Rhizobium. A symbiotic relationship is formed where nitrogen is fixed for the plant and the plant gives carbon that is fixed by photosynthesis, allowing the Legume to survive in poor nitrogen conditions. There are three sub-families: Papilionoidae, Caesalpinioidae, and Mimosoidae. Papilionoidae is the largest of the three sub-families and the most widespread. The majority of the species are herbaceous, but there are a few trees and shrubs. Papilionoidae are recognized for their butterfly-like flowers, which are zygomorphic. Two of the five petals are fused together to form a boat-shaped keel and two petals form wings, while the last is a banner petal. Most of the important crop species are in this sub-family including Glycine max (Soya bean), Pisum sativum (common pea), Cicer arietinum (chickpea), Phaseoulus vulgaris (French bean), Lens culinaris (lentil), and Arachis hypogaea (peanut). Caesalpinioidae are mostly tropical or subtropical trees and shrubs. Root nodules are rarely formed in Caesalpinioidae. The flowers are zygomorphic and have five petals but do not distinguish themselves as in the former subgroup. The stamens are visible externally. Several species are popular ornamentals such as the Delonix regia, whose common name is Flamboyant, and Caesalpinia pulcherrima, known as Barbados Pride. Senna alexandrina is a commercially grown medicinal plant for its purgative qualities. The sub-family Mimosoidae is also mostly tropical and subtropical shrubs and trees. The characteristic defining this sub-group is its small, actinomorphic flowers, which are crowned together into spikes that resemble a pompom. The species Acacia are important economically for timbers, extracts for tanning, and some yield a gum, which is used in industrial processes. The Legume, Leucaena leucocephala, known also as Leadtree has a nutritive value equal or superior to alfalfa. Its qualities have earned a favorable reputation in land reclamation, erosion control, water conservation, reforestation, and soil improvement programs. The leaves are used as mulch on crops and can significantly increase yields. The seeds are strung into beads for various items of jewelry and sold to tourists in Puerto Rico and the Virgin Islands. In the Philippines, the young pods are cooked as a vegetable and seeds are used as a substitute for coffee. Ripe seeds can be eaten like popcorn. The Leadtree is planted to provide shade for crops such as coffee, vanilla, cocoa, and black pepper. The wood is heavy and used for fuel or charcoal. In Latin America the bark of the Leadtree is used medicinally to ease internal pain. A decoction of the root and bark is taken as a contraceptive, ecbolic, or depilatory. Another species of Legume, Enterolobium cyclocarpum, also known as corotu or Guanacaste, is the national tree of Costa Rica. This tree is one of the largest trees in the dry forest of Central America, reaching 3m in diameter and up to 40m in height with a large spreading crown. A providence in Costa Rica is named after this tree because they are abundant over the countryside, creating a distinctive landscape. The pods of the corotu resemble an ear in form; promoting common names such as ear fruit, ear pod, and orejoni (from the Spanish word oreja meaning ear). Like the Leadtree, Guanacaste is planted to shade livestock or crops. Livestock also value this Legume because it produces a large quantity of highly palatable and nutritious pods containing a sugary, dry pulp. The wood has a similar appearance to walnut and is resistant to attack from dry-wood termites. This makes it practical for house construction. The pods and bark are used in soap making and medicinally to fight colds and bronchitis. Fabaceae is a family useful for many things.
Gesneriaceae are herbaceous perennials or annuals, consisting of shrubs, lianas, and trees. Twenty percent are epiphytic. This family is primarily distributed in the tropics but there are a few temperate species. Generally the leaves are opposite and many are “velvety”. A well-known species is the African violet. The species of Episcia is a creeping, tropical perennial native to Brazil, Columbia, Guinea, and Surinam. It is a popular choice for hanging baskets. Another species used in hanging baskets is the Columnea. These tropical plants are natives of South America and form bushy plants with oval or lance-shaped leaves that are dark green. The flowers are tubular and irregularly lobed.
Aeschynanthus x splendidus.................Diastema vexans...............................Kohleria cv. Longwood
Although modern classification limits members of this family to the mallows, abutilons, cotton, and hibiscuses, Malvaceae once also included baobabs, kapok, kola, cacao, durians among others. There are now a total of fifty genera and over 1,500 species characterized by the presence of stellate (star-shaped) hairs and mucilaginious sap. The flowers are typically bisexual and actinomorphic. Commonly the flowers are large and trumpet shaped with a prominent bundle of stamens and carpels. The species Hibiscus esculentus, “okra”, is edible and releases a lot of mucus that gives gumbo its slimy consistency. Montezuma speciosissima is a tree from Puerto Rico that is grown as an ornamental elsewhere but provides durable timber for fence posts and furniture as well. In Brazil the species Abutilon hybridum is found and is known as the “Chinese Lantern”.
Abutilon "Moonchimes".........................Hibiscus rosesinensis
This family consists of perennial herbs that grow from rhizomes. The leaves are alternate and the lateral veins on the blades are parallel. The fruits are fleshy, dry capsules. Calathea insignis, or Rattlesnake plant, belongs to this family. This species is bushy with narrow, tapering erect foliage. Its leaves have wavy edges and can grow to 18 inches long. The top of its leaf is pale green with dark green blotches and its underside is a dark maroon.
This family is a taxon of dicotyledonous flowering plants that is found mostly in the tropics. They are annual or perennial herbs, shrubs, or small trees. Their leaves are distinctive, being opposite with 3-7 longitudinal veins that rise from the base of the blade to the tip of the leaf. A number of species are labeled invasive. An example is Koster’s curse introduced in the 1940’s to the Hawaiian Islands. The berries produced are loved by birds and are therefore spread everywhere, making the plant difficult to control. Another species that is invasive is the Miconia calvescens which is a tree that could take over Hawaii’s forests. It has already claimed 60% of Tahiti’s forests!
There are over 1,000 species in the Moraceae family comprising of trees, shrubs, and rarely herbs. Most have a milky sap. Their leaves are simple and alternate most of the time. The flowers are unisexual and are densely aggregated. Male flowers have four stamens and the female flowers have a bicarpellate pistil with two styles. The fruit types are drupes and achenes. The Broussonetia papyrifera, or paper mulberry, is a shrub or small tree that is native to East Asia. Its bark is converted into fine cloth for skirts, capes, loincloths, sandals, bed cloths, etc. Another genus is the Ficus, which includes figs and rubber plants. Ficus carica, the edible fig, is an example and so is Ficus religiosa, the Buddha Tree that is native to India. Buddha was supposed to receive enlightenment under such a tree and a cutting of this plant dating to 288 BC still exists in Sri Lanka. A better known Ficus is the Indian banyan tree, or Ficus benghalensis. It is the world’s largest tree in terms of spread with some old trees covering up to an acre of ground. “Banyan” refers to the merchants who set up shop under the spreading trees, creating a meeting place for artisans, tourists and children. Attractive red fruits and aerial roots hang from the limbs. The reproduction system of the Ficus is unique. Each species has an associated species of agaonid wasp that is the only way they can pollinate. The wasps pollinate the plant and in turn the plant’s fruit is the only place the wasp can lay their eggs.
Ficus sp................................................Ficus benghalensis.....................Ficus triangularis
Comprised of large tree-like perennial herbs, the Musaceae have alternate leaves with concentric sheathing portions that create pseudo-trunks from which the blades diverge. The blades have prominent mid-rib and parallel lateral veins. The flowers are zygomorphic and unisexual. The fruit is a berry and with a leathery separable ecocarp. Musa x paradisiaca, the edible banana, is the seedless fruit of commerce. Musa papadisiaca ssp. normalis, the plantain, is a form of cooking banana or plantain.
Musa acuminata cv. Enanogigante
This family consists of trees and shrubs found in the tropics, subtropics, and temperate regions. The leaves are usually opposite and frequently glandular dotted. The flowers are actinomorphic and the fruit is commonly a berry. The species Myrciaria cauliflora “Jaboticaba” is a large cauliforous (flowers and fruits grow directly from the trunk or branches instead of from the tips) tree with peeling bark. It is cultivated in Brazil for its edible fruit. The species Psidium guajava “guava” is a shrub from tropical America that has a lemon’s shape and size. This fruit is pink or cream inside and used for jam, jelly, and juice.
Eugenia sprengeri......................................Eugenia paniculata
These herbs, vines, shrubs, and trees are characterized by the presence of betalains and p-plastids. The leaves are simple, entire, epostulate, and usually opposite. The flower is bisexual. The fruit is an achene. The genus Bougainvillea originates from South America and contains species that are evergreen or deciduous. Petal-like bracts hide the flowers of Bougainvillea. The actual flower is white and tubular. This genus is named after the French navigator, Louis de Bougainville, who first discovered these plants. Bougainvillea glabra or “Paper Flower” is a vine in this genus.