Lianes with aerial or clinging adventitious roots, rooting in the soil where the stem touches the ground.Leaves absent, or if present, sessile to shortly petiolate, fleshy.Inflorescences axillary or terminal, few- to many-flowered.Flowers large; white, yellow or green, often marked with purple or yellow on the lip.Sepals and petals similar, free.Lip usually larger than the sepals and petals, adnate to column for part of its length and forming a funnel; disk variously appendaged with lamellae or hairs.Column elongate, curved, auriculate; anther attached to margin of clinandrium, incumbent, subglobose, operculate; stigma transverse, bifid at the apex, situated under the rostellum.Rostellum broad, membranous, articulated at the base, usually deflexed.Capsule long, cylindrical, unilocular, dehiscent; seeds black, relatively large.
Epiphytic, hemiepiphytic or terrestrial, herbaceous vines. Roots produced at each stem node, usually flattened, slender and smooth when free or attached to tree bark, or thick, terete, and villose when in soil. Stems scandent, sparsely or profusely branched, terete or quadrangular, sometimes sulcate, slender to thick, britde to succulent, smooth to warty. Leaves non-articulate, sheathless, distichous or spirally arranged, membranaceous, coriaceous or fleshy, developing conspicuous and persisting blades or scale-like and prompdy deciduous, rarely with a neat petiole. Inflorescence axillary, racemose to paniculate, rarely a complex cyme; similar to the vegetative axes and elongate, bearing leaflike bracts and remote flowers, or different from the vegetative axes and congested, with scale-like bracts on the dense rachis, sometimes intermediate between both extremes; bracts sometimes deciduous. Flowers usually showy, short-lived, produced in succession, resupinate; perianth deciduous once the flower is fertilized; usually gullet-shaped, sometimes strongly fragrant. Sepals free, spreading, flat to contorted and undulate; smooth, rarely granulose or warty. Petals free, often dorsally keeled, spreading, reflexed or undulate-contorted. Labellum completely free (rare) to completely fused to the column margins, forming an open, deeply saccate or funnel-shaped chamber; simple to variously lobed, usually long-clawed, disc with longitudinal keels, trichomes, warts or thickened-rugose veins, often with a penicillate callus formed by a cluster of fimbriate, retrorse scales. Column semi-terete or trigonous, straight to arcuate, often pubescent on the ventral surface, and sometimes with basal keels, foodess; stigma variable, forming a transverse cavity with thickened, sticky margins, or more often the lateral lobes emergent and flap-like; the midlobe of the stigma sometimes with a narrow band of sticky material along the margin (a primitive sort of rostellum), but the viscid material absent in others; anther versatile, terminal, semi-erect, incumbent to hyperincumbent, often subtended by a distinct filament; connective conspicuous, sometimes with horn-like projections; column apex with wings; pollen in monads, not forming distinct pollinia and lacking accessory structures, but sticky and sometimes removed as a triangular unit. Ovary articulate to the perianth, unilocular, rarely with an inconspicuous calyculus; sulcate, smooth, rarely granulose. Fruit a dehiscent capsule to slighdy dehiscent berry, usually opening along two lines and forming unequal valves; sometimes strongly fragrant; with relatively large seeds with a sclerotic seed coat; surface smooth to slightly warty. (MAS).
Scrambling, epiphytic lianes bearing adventitious roots arising at the nodes and opposite the leaves, if any. Stems usually terete, occasionally channelled, succulent, deep olive- or blue-green, of indefinite length, with or without leaves. Leaves remote, linear to oblong-elliptical and broadly ovate, sessile or shortly petiolate, fleshy, often coriaceous, usually becoming smaller towards apex of stem, the uppermost leaves bract-like. Inflorescences racemose, occasionally branched, usually axillary, very occasionally terminal, sessile or pedunculate, few–many-flowered, often only 1 or 2 flowers fully open at one time. Flowers large, subtended by bracts of various sizes, often campanulate, ranging from purest white to deep dull green, often fleshy, fugacious. Sepals and petals free; petals often keeled on dorsal surface. Lip usually larger than tepals, adnate to the column for various distances to form a funnel; disc variously appendaged with lamellae, laciniae, hairs or raised keels. Column elongate, curved, auriculate; anther attached to margin of clinandrium, incumbent, subglobose, operculate; stigma transverse, often bifid at apex, situated under rostellum; rostellum broad, membranous, articulated at base, usually deflexed. Capsules linear, often very long, unilocular, dehiscent; seeds relatively large, black, shining.
Vanilla is a thermophilous group. There are no Vanilla species in montane habitats, and those that have been collected at higher elevations usually have been found in savanna-like vegetation, dry forest on intermountain valleys, and occasionally in lower mountain rain forest. Despite this thermophilous character, species are widespread from subtropical to equatorial forest. In the Americas, the genus is found from Florida in the United States to Misiones, Argentina. Leafless Vanilla species may be found in xeric formations, and at least the Mascarene and Caribbean groups are found in tropical deciduous forest, thorn scrub, and coral buff vegetation. Leafy species are usually found in more mesic environments, although some of them may reach tropical deciduous forest and coastal dune vegetation.
Species with membranaceous leaves are found in moister habitats.
Their brittle stems are not fleshy, and the non-succulent leaves have high stomatal density, traits that apparently do not permit their establishment in seasonal areas. In this group some species may be found at higher elevations, usually in moist gallery forest in savannas. Most Vanilla species are secondary hemiepiphytes that start their life on the ground and climb a tree trunk to reach wellilluminated spots, although the stems rarely reach the upper canopy. Other species, such as Vanilla palmarum, seem to be epiphytes that complete their life cycle in tree (usually palm) crowns. Many other species, although hemiepiphytes, may be found scrambling on rocks and never climbing trees. Crassulacean acid metabolism (CAM) has been reported in Vanilla (Nuernbergk 1964; Dittrich 1976). Many Vanilla species in Central America seem to be limited to particular substrates. For example, the Vanilla planifolia alliance is almost entirely restricted to calcareous or sedimentary substrates, but V insignis Ames may be found on volcanic areas, which are seasonally dry. Some Vanilla species are threatened by habitat destruction/ transformation. The wild populations of the cultivated species, V. planifolia, are considered endangered in Mexico. Considering the rarity of specimens and the densely populated areas where they occur, it is suspected that some species from western Africa are also threatened. (MAS).
In addition to the use of some Vanilla species as ornamentals, vanilla is the sole product from Orchidaceae of significant economic importance in the world today, with an annual production of about 2000 tons. Vanilla exports generate US $60-80 million in foreign exchange for producing countries (Smith et al. 1992), perhaps more at present. Vanilla has a long history, and it is supposed that it was already in use in Mexico before Columbus arrived in America in 1492. The Aztec Indians called it 'tlilxóchiltl', which literally means black flower, but interpreted as 'black pod'. It is said that Cortéz, who conquered Mexico, was offered chocolate flavoured with vanilla in a golden goblet at the court of Emperor Montezuma. A similar beverage is prepared today in remote Indian regions of Mexico, to which red pepper is added. The Spanish conquistadors discovered the secret of the aroma, and Vanilla fruits together with many other treasures were taken to the Iberian Peninsula at the beginning of the sixteenth century. The first botanical notes on the Vanilla plant were made by the famous French botanist Charles de l'Ecluse (Clusius), a professor at the University of Leiden. In 1602 he received several Vanilla plants from Hugo Morgan, pharmacist to Queen Elizabeth I of England. He described the plant by the name of Lobus oblongus aromaticus. At this time the term vaynilla (=small pod) was used by the Spaniards for the fruit, and the Latinized version, vanilla, was used by Piso in 1658. The first person to use the genus name Vanilla in writing was Father Plumier in 1703 (Bouriquet 1954). Vanilla plantations have been recorded since c. 1760, near Papantla, in the Totonaco country in northern Veracruz. Before this, vanilla fruits were probably gathered from wild vines in southern Veracruz (Acayucan) and northern Oaxaca (Teutila). At the end of the eighteenth century hundreds of thousands of fruits were exported to Europe from the port of Veracruz, but these were grown or gathered in Misantla, Teutila, and Papantla (Humboldt 1811). At the turn of the nineteenth century, the then Marquess of Blandford reintroduced it into England. In 1807, the vanilla of commerce was cultivated successfully in England by Charles Grenville,who supplied cutrings to botanical gardens in France and Belgium (Childers et al. 19 59). At this time it was difficult to get plants to set fruit in Europe because of the lack of suitable insect. pollinators. Introduction of bees from Mexico proved to be unsuccessful, and although artificial pollination gave better results, it was time consuming.
However, in 1841 Edmund Albius discovered a quicker, more practical method, which was used throughout the vanilla-producing countries (Childers et al. 1959). Artificial pollination was apparently practiced in Mexico soon after 1840, when a member of the French colony at Jicaltepec, Veracruz, brought back with him the technique after he was sent to France to study tropical agriculture; almost immediately the technique was adopted by Totonaco indians, with a spectacular increase in vanilla production (Bruman 1948). Natural pollination in the wild and plantations is usually extremely low in the native areas. In spite of the many difficulties associated with its cultivation (pollination, fungal diseases, etc.) and time-consuming production, vanilla has become one of the most widely used flavourings in the world. The most important species for the production of vanilla is V planifolia, which is indigenous to Central America, from eastern Mexico to Costa Rica (Soto, unpublished data). It is also cultivated widely throughout the tropics and often found escaped from cultivation. Two other species are grown commercially, V pompona and V tahitensis, but their vanilla is of a different chemical composition and an inferior quality and therefore commands a lower price in the market than that of V planifolia. Vanilla pompona is usually called pompona vanilla or vanillon. It is mainly cultivated in Guadeloupe and can be grown under more adverse conditions than V planifolia. It is also more resistant to the vanilla root rot disease caused by Fusarium batatis var. vanillae, and flowers after 1-2 years of planting, whereas cuttings of the same size of V planifolia do not usually flower until the third year. Vanilla tahitensis is found in Tahiti and other Pacific islands, including New Guinea, and is also cultivated in Hawaii. Aromatic Vanilla fruits are apparendy an adaptation to bat dispersal and seem to be found in all the leafy American species, except in the group of species with membranaceous leaves. Therefore, aromatic fruits are known or expected from 35 species, including V. appendiculata Rolfe, V. bicolor, V. calyculata Schltr., V. chamissonis Klotzsch, V. cribbiana Soto Arenas, V. dressleri Soto Arenas, V. fimbriata Rolfe, V. gardneri Rolfe, V. grandijlora Lindl., V. hamata Klotzsch, V. hartii Rolfe, V. hostmannii Rolfe, V. insignis, V. odorata Presl, V. palmarum, V. phaeantha Rchb.f., V. ruiziana Klotzsch, V. trigonocarpa, and V. vellozii Rolfe (besides the cultivated ones in which they are well documented; Porteres 1954; M. Soto, unpublished data). Some of these species are cultivated locally or gathered from the wild, but they are not of economic importance. In Mexico, Indian women hold the fruits of V. pompona in great esteem and prepare them with oil before applying to the hair. The fruits of widespread V. odorata are also collected in many American countries as a V. planifolia substitute and give fragrance to rums.
Reports of aromatic fruits in V. bertoniensis Bertoni and V. perexilis Bertoni (=V. parvifolia Barb.Rodr.) have not been confirmed, since the available specimens have dry, dehiscent fruits with no trace of odour. Some Caribbean and Asian species, such as V. claviculata Sw., V. grzjjithii Rchb.f., and V. abundijlora J.J.Sm. produce fleshy, sometimes edible fruits that seem to be dispersed by animals. Vanilla extract is used to flavour ice cream, confectionery, cola soft drinks, tobacco, and is widely used in bakery and perfumery. The roots of some species (e.g. V. grandifolia Lindl. and V. ova/is Blanco) are used to prepare fishing nets and baskets (see Lawler 1984). Leafless Vanilla stems are used in Madagascar to prepare aphrodisiacs, and the fruits of V. planifolia are thought also to have aphrodisiac properties. Other species in America, Asia, and Africa have been used in folk medicine (Lawler 1984). In Mexico V. planifolia flowers were used as charms, and the fruits are at present widely esteemed as charms to scare away evil spirits. Global demand for natural vanilla outstrips supply. Vanilla substitutes, such as tonka bean (Dipteryx species; Fabaceae), synthetic vanillin, and the new approaches to culturing Vanilla cells in vitro for producing 'natural vanilla' are unlikely to influence the market for field-grown and village-cured vanilla, just as there are no substitutes for wine or olive oil. If the trend to return to natural products persists, vanilla will continue being an important resource for developing tropical countries (NV, RG, MAS).