CLASS LILIOPSIDA – Diversity of Life

CLASS LILIOPSIDA (Batsch 1802)

EUKARYA> ARCHAEPLASTIDA> VIRIDIPLANTAE> STREPTOBIONTA> EMBRYOPHYTA> TRACHEOPHYTA> SPERMOPHYTA> ANGIOSPERMOPHYTA> LILIOPSIDA

ANGIOSPERMOPHYTA LINKS

Phylum Angiospermophyta

Class Nymphaeopsida

Class Magnoliopsida

Class Ceratophyllopsida

Class Asteropsida

Liliopsida (li-le-OP-si-da) is derived from the genus Lilium, the Latin word for lily. The suffix is derived from the Greek for “that which resembles” (opsis -οψισ). Together, they mean that which resembles a Lily.

INTRODUCTION TO THE LILIOPSIDA

The Liliopsida (also called the monocots) range from tiny floating plants to common herbs and epiphytes to large rosette trees. However, despite their diversity in growth habit, the monocots are decidedly monophyletic with an array of distinctive characters that include: leaves with parallel veins, monocot condition in the seed, monosulcate pollen; three-merous flowers in two whorls, and atactostelic stems. They are made up of 11 orders, some of which form a monophyletic group called the Commelinid Clade, a collection of taxa that include palms and grasses. Because the monocots are not eustelic, but have scattered vascular bundles (atactostele), they do not make wood though the palms and bamboos can appear to be almost woody.

We will illustrate the diversity of the class by highlighting some of the important families. Resolution of the positions of the seven Non-Commelinoid Orders indicates that they are nested according to APG III (2009; see Figure 1). In earlier phylogenetic treatments (e.g. APG I 1998, APG II 2003, and Judd et al. 2002), the orders Liliales, Asparagales, and Dioscoriales were considered to constitute a monophyletic group called the Lily Clade, a group that would be paraphyletic according to APG III (2009). The Commelinoid Orders do make up a monophyletic group that can be identified by molecular means; however, morphological or biochemical synapomorphies are unclear. The following text describes some of the the major orders and families of the Liliopsida. Click on the highlighted ordinal and family names to see the context of the group within the more complete taxonomic system of APG III (2009).

THE NON-COMMELINOIDS (BASAL MONOCOT ORDERS)

ORDER ACORALES

ACORACEAE

This family was only recently recognized (e.g. APG III 2009) as basal to the rest of the monocots and quite distinct from the Araceae, with which it had been associated in morphological taxonomic systems like Cronquist (1981). The order has only a single genus (Acorus) of wetland plants, which occur in the temperate zone of the northern hemisphere. Flowers occur in spikes of reduced flowers but there is no spathe (Figure 2). These appear to be the oldest surviving line of monocots.

ORDER ALISMATALES

This order is well defined by molecular analyses; however, morphological synapomorphies are unclear. Some synapomorphis may be the occurrence of stems with small scales, glandular hairs within the sheathing leaf bases, extrorse anthers, and large embryo within the seed. This order has 13 families. Alismataceae and Araceae represent characters of the order.

ALISMATACEAE (includes Limnocharitaceae; Water Plantain family)

These plants are perennial aquatic or semi-aquatic herbs. Axes have much aerenchyma (text with tooltip) , and xylem (text with tooltip) is only sparsely lignified (text with tooltip) with vessels (text with tooltip) confined to roots (text with tooltip) . Vascular bundles (text with tooltip) are scattered or in 2 concentric rings. Leaves are alternate and clustered at the tip of the rhizome (text with tooltip) and somewhat ensheathing at the base. Sometimes the leaves are differentiated into petioles and blades. The inflorescence (text with tooltip) usually organized in cymes or racemes (text with tooltip) (e.g. Figure 3). The flowers actinomorphic (text with tooltip) and 3-merous (3 green sepals (text with tooltip) and 3 white petals (text with tooltip) ). Stamens (text with tooltip) are variable and range from three to many. Pollen (text with tooltip) usually has many pores. Gynoecium (text with tooltip) has 3-20 apocarpous (text with tooltip) (separate or unfused) pistils (text with tooltip) , each with 1-many ovules (text with tooltip) .

ARACEAE (Arum family)

Usually these plants are herbs, but rarely vines or shrubs. Leaves are alternate and basal (text with tooltip) . Leaves have sheathing petioles and the leaf blades are expanded with reticulate or net veins. Inflorescence is a spadix (text with tooltip) subtended by a spathe (a bract (text with tooltip) ) with tiny perfect (text with tooltip) or imperfect (text with tooltip) flowers. Perianth (text with tooltip) is often tiny or missing. Pollen grains have 2-3 nuclei and usually a single aperture. The gynoecium has three fused carpels. The fruit is a berry (text with tooltip) or a multiple (text with tooltip) . Mature seeds have a large embryo in copious oily endosperm (text with tooltip) .

ORDER LILIALES

Plants in this order usually are geophytic (text with tooltip) perennial herbs, growing by bulbs or corms. Vessels are confined to the roots, and leaves (text with tooltip) usually are simple and entire. The outer whorls of the flowers are tepals (text with tooltip) in two series of three segments, each. Nectaries are at the base of the tepals and stamen filaments (text with tooltip) , but there are no septal nectaries. Usually there are as many stamens as tepals, and pollen is binucleate. The gynoecium can be either epigynous (text with tooltip) or hypogynous (text with tooltip) and usually of three fused carpels. Fruit (text with tooltip) usually is a capsule (text with tooltip) but often a berry or drupe (text with tooltip) . Seeds (text with tooltip) when mature have abundant endosperm (hemicellulose, oil and protein). This order has 10 families, of which Liliaceae is the representative family.

LILIACEAE (Lily family)

Members of this family are geophyte herbs that grow from bulbs with contractile roots. The megagametophyte develops from 4 megaspores such that the endosperm is pentaploid. The work of APG I (1998), APG II (2003), and APG III (2009) has split the lilies into several other families, some into another order. Those taxa that are retained in the family are economically important. Taxa like Lilium (Figure 5) and Tulipa (Figure 6) are large and showy which makes them favorites of the perennial gardener. Tulip culture was the first horticultural craze in Western Europe and began in the 16th century after tulips were brought from the Ottoman Empire. The early 17th century saw what became known as tulip mania, and their bulbs were used as a form of exchange. Although the speculative bubble burst, the love of tulips never died, and they are now among the most commonly grown spring perrentials.

ORDER ASPARAGALES

This order has characteristic seeds in which the outer integument (text with tooltip) is missing or reduced to a black phytomelan crust (a character that is lost in the orchids). Tepals are often without spots, and nectaries are part of the ovulary (text with tooltip) (not at the base of the tepal). This order has 14 families and 26,800 species.

ORCHIDACEAE (Orchid family)

Orchids are epiphytic (text with tooltip) , geophytic or terrestrial herbs that tend to be strongly mycotrophic. Leaves usually have ensheathing leaf bases; but sometimes the leaf is highly modified. Flowers (text with tooltip) (see Figure 7) are strongly zygomorphic (text with tooltip) , epigynous, three-merous, and often with only one to two stamens. Pollen is binucleate and monosulcate (or exine lacking entirely). Gynoecium is formed of three fused carpels, which form a capsular fruit. Seeds are very numerous, tiny, and without endosperm. The embryo usually has only a few cells (thus, usually cotyledon undifferentiated).

The Orchidaceae is a very large and diverse family with nearly 800 genera and >21,950 species and are found in almost all terrestrial environments on earth and range from epiphytes, to vines, to geophytic herbs. Analyses by Cameron et al. (1999) and Freudenstein et al. (2004) have confirmed that orchids are divided unevenly between five monophyletic subfamilies (Figure 8). There is strong support for the sister relationship between Orchidoideae and Epidendroideae; however, the relative positions of Apostasoideae, Vanilloideae, and Cypripedoideae are not supported.

The Vanilla Orchid (Vanilla; Figures 7 & 9) is a vine whose fruit is a capsule with many tiny seeds. Both fruit and seeds are impregnated with vanillin, a fat-soluble aromatic compound. The plant was used by Mesoamericans as a flavoring for chocolate and brought to Europe in the early 16th Century (Schery 1972).

Most orchids are grown for their flowers and they are used as corsages and high-end potted plants [e.g. Cattleya (Figure 10) and Phalaenopsis (Figure 11)]. Interest in orchids and orchid culture became a frenzy in western Europe during the middle 19th Century. Similarly, Darwin became interested in orchids and began an intense study of them. He wrote a book about his studies, The Various Contrivances by which Orchids are Fertilised by Insects, in 1862, only a few years after publication of The Origin of Species. He used the book to demonstrate the power of natural selection and the concept of coevolution (orchids and their pollinating insects). Although the book received praise from Botanists like J. D. Hooker and Asa Gray, it was greeted with indifference by the general public which wanted to read real controversy about human origins. Darwin did make one prediction, though, based on the remarkably long nectary spur of the epiphytic orchid, Angraecum sesquipedale (Figure 12), from Madagascar. The pollinator was not known at the time of his writing; so, Darwin predicted that there would be a moth on Madagascar with a proboscis as long as the nectary spur (27-42 cm long). Such a moth was found in 1903, 21 years after the death of Darwin.

Orchid pollen is large and bound together with other pollen grains in a waxy structure called a pollinarium. Thus, it must have the pollen transferred to other plants by an animal vector. Like Angraecum and its pollinator, most orchids have evolved very close pollinator associations. This assures that after the animal has acquired the pollinarium, it would be enticed to visit a member of the same species. Such plants might provide a reward like nectar, or they might fool the would-be pollinator into interpreting its lip petal as a receptive female. Often, this ruse is accompanied by the release of appropriate pheromones to attract the male.

Ramirez et al. (2007) report a beautifully preserved stingless bee in amber from the Miocene 15-20 MYA in the Dominican Republic. The bee had two orchid pollinaria stuck to the back of its thorax. This is one of the earliest bits of direct evidence of insect pollination. The characters of the pollinarium are so well-preserved that they assigned them to a genus in the Orchidoideae, a member of the crown group (Orchioideae + Epidendriodeae). Furthermore, they apply a molecular clock to a survey of extant orchids which were timed by the polliniaria. Their results suggest that the family appeared in the upper Cretaceous, much older than more recent predictions (e.g. Labandeira 1998). Presumably, insect-orchid associations have been established throughout the history of this family.

Geophytic orchids are more typical in temperate and subarctic regions. The Pink Ladyslipper or Moccasin Flower (Cypripedium acaule, Figure 13) is a member of the community of spring ephemerals that appear in the acid-soil woodlands of the northeastern US and adjacent parts of Canada. The plants emerge above the ground in May and flower from the last part of May to the middle of June. The flower has an inflated lip petal with slit. The pollinator, a bee, is enticed by the color and odor to enter the lip petal through the slit, which then closes behind the insect. While the bee seeks escape, it must move up past a stigma and a stamen, where it is tagged with a pollinarium and then out through a hole in the top of the lip petal. When the bee enters the next flower, it deposits the pollinarium on the stigma.

Though most orchids are mycorrhizal, a few have an obligate mycorrhizal relationship through most of their lives. In general, mycorrhizal orchids utilize soil fungi like Armillaria and, thereby, get some of their carbon by the digestion of dead organic matter in the soil. Corallorhiza (Figure 14) assimilates more than 70% of its carbon through its association with soil fungi such that Zimmer et al. (2008) describe the orchid as a parasite of the fungus.

Although the pollen is large and glued together in pollinaria, the seeds are very tiny, with only a few cells. The tiny seeds are released by a bean-like capsule and are wind-dispersed. Successful germination depends not only on landing in a proper location, but also on the success of the seed to enter into a relationship with a fungus. I suppose that such associations must also be acquired by epiphytic taxa. If so, the epiphyte depends upon a woody plant for its place of growth, the fungus for assimilation of necessary compounds, and the animal for the pollination of its flowers.

COMMELINOID CLADE

The commelinoid clade has been recognized as a monophyletic since Chase et al. (1993). There are no clear morphological synapomorphies in this large and diverse group. It has four orders with a basal unassigned family (Dasypogonaceae).

ORDER ARECALES

ARECACEAE (Palmae; Palm family)

The Palm family is the single family in this order. The palms appear to be the sisters to all other taxa in the commelinoid clade. They are slender trees or stout shrubs with unbranched trunks that are covered by persistent leaf bases. The leaves are evergreen, alternate, and compound (pinnate or palmate). The leaf bases are very large and form basal sheaths from which a petiole emerges. The stems have no axillary buds. The inflorescenses are large, paniculate, and subtended by one or more spathes. Flowers may be perfect or imperfect; and the plants may be monoecious or dioecious. The flowers are actinomorphic with three sepals and three petals. They have six stamens in two series of three. The gynoecium is a compound pistil of three fused carpels. Fruits may be berries or drupes. Seeds have a large amount of endosperm and a very small embryo.

The earliest known fossils of palms are from the upper Cretaceous (Prasad et al. 2005); thus, they separated very early from the other lines of monocots. Schery (1972) claims that the Date Palm (Phoenix, Figure 15) was domesticated 8,000 years ago in the deserts of the Middle East. The fruit (a drupe) is high in sugar and can be preserved by drying, making it a staple of the nomadic desert people. Because it is dioecious, plantations of fruit-bearing plants can be fertilized by a few staminate plants.

Coconuts (Cocos, Figure 16) make a very large fibrous drupe that is well adapted to dispersal by ocean currents. The seeds of Cocos and its relatives are the largest in the plant kingdom. Indeed, Coco-de-Mer (Lodoicea, Figure 17), the double coconut, produces the largest seed (up to 30 kg), which takes up to 10 years to ripen.

ORDER POALES

The monophyly of this group is well supported. Morphological synapomorphies include silica bodies in the epidermis, styles (text with tooltip) separate or strongly branched, no septal nectaries or raphide crystals. This order has 18 families and 14,500 species.

BROMELIACEAE (Bromeliad family)

Bromeliads usually are epiphytic herbs (sometimes terrestrial). Leaves are alternate and forming a rosette, many of which are adapted to collecting rain water. Flowers are perfect and well-adapted to insect pollination (Figure 18). Pollen grains have 2-3 pores. The fruit usually is fleshy (a berry) or a capsule. Embryo is variable, small to large, and the seed has copious, mealy endosperm.

The terrestrial plant, Ananas (pineapple, Figure 19), is the best-known and most economically-important member of this family. The center of origin for pineapple is thought to be northern Argentina and Brazil, where several wild species of Ananas persist (Schery 1972). The domestication of the pineapple must have occurred very early by the indigenous peoples of southern Brazi. By the time Columbus came to the Americas, he found pineapple in the West Indies and brought it back to western Europe. There, methods for its cultivation and propagation were explored. The pineapple became a symbol of hospitality by the 19th century. The demand for pineapple grew beyond the few that greenhouses could provide, and western European powers began to establish plantations in their tropical holdings. At the beginning of the 20th century several pineapple plantations were established on Oahu.

Tillandsia (Figure 20), a large genus of more than 500 species, is known by several common names: Spanish moss, air plant, and Ball moss. It is an epiphyte that resembles gray-green tufts of hair on limbs of trees and grows through the neotropics with some able to withstand low temperatures down to -10C. The species that occur through the southern states of the US provide iconic images of stately Live Oaks festooned with Tillansdia. These plants have been used as packing material, add-ons to other potted plants, and, now more frequently, as plants to culture themselves. Often these are wild collected and some are on threatened and endangered lists of some southern states.

Most bromeliads cover large trees like Ficus in neotropical wet forests (Figure 21). Typically, these epiphytic plants make a very tight rosette of leaves that serves to capture and hold rain water (Figure 22). Such pools high in the trees serve as sources of drinking water and breeding places for vertebrates such as frogs and many species of insects. In short, the ponds created by bromeliads contain their own small ecosystems and may house a hidden diversity in the rainforest.

POACEAE (Gramineae; Grass family)

Grasses are perennial herbs (rarely annual), sometimes woody, but always without secondary growth. Cell walls often contain silica. Leaves are in 2 ranks (text with tooltip) , each leaf with a basal sheath and a narrow parallel-veined blade. An adaxial ligule (text with tooltip) is usually present at the junction of the sheath and blade. Flowers very small and organized into spikes (text with tooltip) or spikelets (text with tooltip) which form secondary inflorescences. The flowers are perfect or imperfect, and each one is enclosed by a pair of scale-like bracts. Pollen grains are trinucleate and have one aperture. This is a very large family that includes the most economically important food species (sugar cane and almost all of the grains). The family has 12 subfamilies (see Figure 34) that are divided between two large groups and a few basal families according to the Grass Phylogeny Working Group (2001). The Poaceae is the fourth largest plant family with 10,025 species.

The grass fruit, the grain or caryopsis, is a thin seed-coat-like layer around a seed rich in protein and carbohydrate. The outer layer is the bran, and the small embryo is the germ. Grains are surrounded by specialized scruffy bracts, the palea and lemma. The spikelet also is subtended by a pair of bracts called glumes (Figure 23). Usually, the spikelets are organized into secondary inflorescences (e.g. Figure 24).

TABLE 1. Important grass grain plants of the world, their generic names, and the regions of the Earth where the plants were domesticated. Much of this information came from Glemin and Bataillon (2009).
GRAIN	GENERIC NAME	REGION OF DOMESTICATION
Rice (Figure 25)	Oryza	Asia
Wheat (Figure 26)	Triticum	Middle East
Maize (corn; Figure 27)	Zea	Central America
Barley	Hordeum	Middle East
Pearl Millet	Pennisetum	South Africa
Foxtail Millet	Setaria	East Asia
Proso Millet	Panicum	Asia
Finger Millet	Eleusine	Ethiopia
Rye	Secale	Turkey
Oats	Avena	Middle East
Sorghum (milo)	Sorghum	Northern Africa

The grass family is the most important plant family to our species. According to the Food and Agriculture Organization of the United Nations, sugar cane, maize (corn), rice, and wheat, all grasses, topped global crop production in 2008. The importance of grain-bearing plants has been with our species for thousands of year. The early cultural centers of the lower Nile and the Fertile Crescent were flood plains where wild grasses grew in abundance.

Such an abundant and rich food source was available only during a short period of time between the maturation of the seed and shattering of the ear (the name for the typical spike of spikelets). If the ears shatter, the seeds scatter and cannot be gathered; so, groups had to occupy an area during the time in which the grains were likely to mature. After collection, the grains had to be kept dry and safe from consumption by vermin and other groups of people. In short, as humans began to rely on grains for food, they needed to control an area, cooperate to gather grain, build structures to house the grain, and a military to protect what they had. The nature of grasses, then became the basis for the development of high culture. This same story played out in Asia with rice, Africa with sorghum and millet, and the Americas with maize. See Table 1 for a more comprehensive list of important grain plants of the world.

Plant agriculture began with the selection of certain grains that had useful properties. Among the most important was the selection for grasses that had non-shattering ears. This allowed the grains to be harvested at the same time. The selective breeding (genetic engineering on a long temporal scale) led to many different varieties of various grains. Wheat (Figure 26) alone has been bred to become the foundation of flat bread, leavened bread, pasta, and noodles. Other grains, like barley have been used for breads and other foods, but they also have been used as the basis for making beer and distillates of beer like whiskey.

Rice (Figure 25) is different from most of the domesticated grasses in that it is a wetland plant and its culture requires the regulation of standing water. Rice is grown in shallow flooded fields called paddies. Rice culture still requires much manual labor in planting, thinning, and harvesting.

Maize (Figure 27) went through a remarkable transformation from ancestral teosinte in Mexico to the present diversity of corn. Matsuoka et al. (2002) give compelling evidence that modern domesticated maize is the result of a single domestication around 9,000 years ago in the southern Mexican highlands. Although the teosinte kernels are very small and hard, they do pop like popcorn when heated. The pistilate ears of teosinte are small with the kernels arranged in two ranks. By 7,000 years ago, the pistillate ears had become modern in form and kernels were larger.

Sugarcane (Saccharum, Figure 28) is a group of large tropical grasses that originated in Southeast Asia and India. According to Watson (1983) the earliest culture of sugarcane began in the Indus Valley about 5,000 years ago, and Arabs brought it to the Mediterranean region by 700 A.D. Cultivation began by Europeans in 1400, and Columbus took sugarcane to the West Indies on his second voyage. Sugarcane efficiently converts sunlight into carbohydrate, much of which is stored as sucrose. The removal of sugar from the cane relies on its solubility in boiling water. Thus, sugar can be removed quite easily and then crystallized.

The subfamily Bambusoideae, the bamboos is a very large and has more than 10,000 species. Bamboos grow by a branching rhizome system with emergent leafy culms. The stems are woody, but without a cambium. Although some bamboos are edible, most that are of economic value are used for building materials, etc. In remote regions of China, bamboo forests support the remaining wild pandas, which feed upon the shoots and leafy branches that they remove by a thumb-like extension of a wrist bone. In other areas, particularly the neotropics, species of bamboo have become exotic invasive pests.

The grass family appeared in the Cretaceous where it may have coevolved with herbivorous dinosaurs (Piperno and Sues 2005, and Lloyd et al. 2008). Prasad et al. (2005) present compelling evidence that recognizable grass phytoliths occurred in the copralites of titanosaur sauropods from the Indian subcontinent. The implication is that grasses had already spread and established themselves in Gondwanaland before the separation of India. Through much of the Tertiary, grasslands spread and produced abundant sources of food which mammals quickly began to exploit. Grass organs (stems and leaves) are tough and impregnated with silica. Thus, the utilization of this resource required cheek teeth adapted to the abrasive nature of grasses. Also, they required fermentation chambers in which cellulose could be digested into usable components. Thus, the ungulates co-evolved with the grasslands.

Similarly, a long-term drying period which began about about 6 million years ago opened the vast north African forests into savannahs (Figure 30). In such an environment, a diverse set of species sprang from the bipedal line of chimpanzees. These were able to take advantage of the rich sources of food, both plant and animal, that the savannah provided. From that line and once rich diversity of hominins only one, the anatomically modern humans which appeared less that 200,000 years ago, remains.

CYPERACEAE (Sedge family)

These plants are herbs, usually of wetlands (Figure 31). Stems typically are triangular in cross section (the mnemonic that I learned as an undergraduate was Sedges have wedges). Leaves are alternate and 3-ranked; the base of the leaf is a closed sheath around the stem and continues with a free blade (as in the grasses). The inflorescence is a spikelet (as in the grasses). The flowers may be perfect or imperfect, in which case the plant is monoecious. The flowers are subtended by bracts and the tepals are reduced to scales, if present. The androecium is usually of 1-3 stamens. The gynoecium is of 2-3 fused pistils. The fruit is an achene or nutlet. The family has 104 genera and 4,500 species.

ORDER ZINGIBERALES

They are perennial herbs that grow from large, often starchy rhizomes. Leaves are opposite or spiraled and usually parallel-pinnate with a distinct petiole. Inflorescences are subtended by bracts, and the flowers are perfect or imperfect. Flowers have six stamens, although rarely are all six functional. Gynoecium often of 3 fused pistils. Fruit variable; dry or fleshy; dehiscent or indehiscent. Seeds with endosperm and copious, starchy perisperm. 7 families

MUSACEAE (Banana family)

Bananas and plantains, this family grows as rosette trees (Figure 32) which terminate in a bisexual inflorescence that can be up to 2 meters long (Figure 33). Bananas and plantains that are currently under culture are sterile hybrids, generally triploid, and seedless (Schery 1972). The family has a native range that extends from New Guinea to Africa, all tropical. The plantation bananas came from New Guinea. From there, they were carried to the islands of the tropical Pacific by Polynesians. Later, Arab traders spread culture of the plant westward to Africa and warm parts of Europe. During the European colonial period, bananas were plantation grown in Africa, India, the West Indies, Central, and South America.

LITERATURE CITED

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By Jack R. Holt. Last revised: 04/06/2014


FIGURE 2. Acorus, Sweet Flag, produces a spike from certain of its Cat-Tail-like leaves. Image by Robert H. Mohlenbrock USDA, in Public Domain	FIGURE 3. Sagitaria latifolia is a wetland plant with arrow-like leaves. The flowers are actinomorphic with three showy petals and many separate pistils. Image by Robert H. Mohlenbrock USDA, in Public Domain	FIGURE 4. Arisaema is an ephemeral plant with three-parted leaves. The inflorescence is a spike of bisexual flowers (staminate flowers at the base of the spike, pistillate flowers at the tip). The inflorescence is subtended by a bract. Image by Robert H. Mohlenbrock USDA, in Public Domain	FIGURE 5. Lilium produces actinomorphic flowers with showy tepals, six stamens, and a pistil with a three-lobed stigma. Image by Ron Moodycliffe, in Public Domain	FIGURE 6. Tulipa is similar to Lilium, but the flowers usually are solitary. Image by John O’Neill in Canberra, Australia. Creative Commons License.


FIGURE 15. Phoenix, the Date Palm, is in full fruit. Image in the Systematic Biology Image Archive.	FIGURE 16. Cocos, the Coconut Palm. The fruits are green and clusters of them are subtended by a long, narrow bract. Image by Iaminfo and used according to the GDFL license.	FIGURE 17. Lodoicea maldivica, the Double Coconut, produces the largest seeds in the flowering plants. Note that the plant has smaller fruits that are just developing. Image by Praslin and used according to the GDFL license.	FIGURE 18. Bilbergia, an epiphytic bromeliad displaying a spike of flowers. Image in the Public Domain.


FIGURE 19. A field of pineapple (Ananas) in Hawaii. Image in the Systematic Biology Image Archive.	FIGURE 20. Tillandsia usneoides in McBride Garden, Hawaii. Image by Gh5046 and placed in the Public Domain.	FIGURE 21. Epiphytic bromeliad on a Ficus at the Baltimore Aquarium. Image in the Systematic Biology Image Archive.	FIGURE 22. Pool formed by the rosette of leaves by an epiphytic bromeliad. Image in the Systematic Biology Image Archive.


FIGURE 23. Wheat (Triticum) Spikelet with the specialized bracts labeled. Image by Aelwyn, used according to the Creative Commons License.	FIGURE 24. Meadow Foxtail Wheat (Alopecurus pratensis), a perennial Eurasian grass in flower. Image by Fir002, used according to the GFDL License.	FIGURE 25. Oryza, rice, nearing maturity. Image from the Systematic Biology Image Archive.	FIGURE 26. Triticum, Wheat nearing maturity. Image from the Systematic Biology Image Archive.


FIGURE 27. Zea, Maize (Corn), nearing maturity. Image from the Systematic Biology Image Archive.	FIGURE 28. Saccharum, Sugarcane, remains one of the leading sources of sugar. This image of a sugarcane plantation is a mural in the Louisiana State Museum was created by Billy Hathorn. Image used according to the GFDL License.	FIGURE 29. Bamboo, a perennial “woody” grass. This was taken from a park in Kyoto, Japan. Image by Paul Vlaar and used according to the GFDL License.	FIGURE 30. African Savannah; gragges with scattered Acacia. Image from the Systematic Biology Image Archive.


FIGURE 9. Vanilla is a vining orchid whose fruit is used to make the flavoring named after it. Note the asymmetry formed by the lip petal. This image also is in Figure 7, which shows a longitudinal section of a Vanilla flower. Image by JoJan in the Florida Everglades, National Park Service; in the Public Domain.	FIGURE 10. Cattleya has been bred into many different showy cultivars. The flowers are sturdy and, therefore, used as corsages. This species, C. aclandiae, is named for Sir Thomas Ackland, the first European to grow orchids with success. Image by Orchi; used under the GFDL License.	FIGURE 11. Phalaenopsis has a flattened display of petals and sepals with a complex lip petal. Image by Carlos Costales Teran; used under the GFDL License.


FIGURE 12. Darwin (1862) speculated that this orchid, Angraecum sesquipedale, which has a nectary spur more than 40 cm long, must have a hawkmoth pollinator on Madagascar with a proboscis as long as the spur. This image comes from a Thomas William Wood, who illustrated an article for Alfred Russel Wallace (1867). The pollinator was found in 1903. Image in the Public Domain.	FIGURE 13. Cypripedium acaule, the Pink Ladyslipper, is a pleasant sight in the northeastern deciduous woodlands. The flower entices a bee to enter the slit in the inflated lip petal. However, the petal snaps shut and the bee has to crawl out an opening at the center of the flower. In doing so, the bee has to crawl over the stigma and pollinaria. Cross pollination requires that the bee must be fooled into doing that again. Image released into the Public Domain by the author.	FIGURE 14. Corallorhiza is uses soil fungi to acquire up to 70% of their assimilated carbon. Image by R. G. Johnson, National Park Service; in the Public Domain.


FIGURE 31. Plate of Eleocharis dulcis, Water Chestnut, from Flora de Filipinas by Fransisco Manuel Blanco (1880). Image in the Public Domain.	FIGURE 32. Dwarf Banana (Musa). Image from the Systematic Biology Image Archive.	FIGURE 33. Banana (Musa) inflorescense. The staminate flowers are terminal and still covered by bracts. The whole inflorescence is almost 2 meters long. Taken in Costa Rica. Image from the Systematic Biology Image Archive.

CLASS LILIOPSIDA (Batsch 1802)

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