408 PLANT MORPHOLOGY 



member is the spiderwort (Tradescantia) , but the pineapple (Ananas) 

 belongs here and also the "long moss" {Tillandsia) of the Southern 

 United States. The flowers are regular or nearly so, mostly trimerous 

 and pentacyclic, hypogynous or sometimes epigynous, and syncarpous. 

 The perianth may or may not be differentiated into a calyx and corolla 

 and the latter may be bract-like or petaloid. A special feature is the 

 presence of mealy (farinose) endosperm. 



Liliales. The Liliales are the great central order of monocotyledons. 

 They number about 5,000 species, most of which are herbs. They are 

 grouped into 9 families, the principal ones being the Juncaceae, Liliaceae, 

 Amaryllidaceae, and Iridaceae. The Juncaceae include the rushes {Jun- 

 cus). The Liliaceae contain such well-known genera as Trillium, Ery- 

 thronium, lily (Lilium), tulip (Tulipa), hyacinth (Hyacinthus), onion 

 (Allium), and Yucca. The Amaryllidaceae are represented by the tube- 

 rose (Polianthes), Agave, and Narcissus. The Iridaceae comprise the 

 flags (Iris), Crocus, Gladiolus, etc. 



The flowers are mostly regvdar and have a perianth consisting of two 

 trimerous whorls that are nearly always alike, being bract-like in the 

 Juncaceae and petaloid in the other families. They have mostly six 

 stamens (three in the Iridaceae) and a tricarpellary pistil. The flowers 

 are either hypogynous (Juncaceae and Liliaceae) or epigynous (Amaryl- 

 lidaceae and Iridaceae). 



Scitaminales. Here belong 4 families and about 1,000 species of mostly 

 tropical herbs, including Canna, banana (Musa), and ginger (Zingiber). 

 The perianth, displaying a special type of irregularity, is composed of two 

 whorls that are often entirely petaloid. All members are epigynous. 

 Generally only one fertile stamen is present. The pistil is tricarpellary 

 and the ovary trilocular. 



Orchidales. This is the highest order of monocotyledons as well as the 

 largest. It comprises 2 families and about 15,000 species of herbs, nearly 

 all of which belong to the Orchidaceae. The orchids reach their greatest 

 display in the tropics, where most of them are epiphytes. The flowers of 

 the Orchidaceae are irregular, epigynous, and syncarpous. The irregu- 

 larity is of a special type. The perianth consists of two trimerous whorls, 

 one petal being strikingly different from the others. The stamens are 

 reduced to three, but these do not belong to the same whorl ; usually only 

 one stamen is fertile. The pistil is tricarpellary and the ovary unilocular. 

 The seeds are without endosperm. 



COMPARISON OF GYMNOSPERMS AND ANGIOSPERMS 



The most important distinguishing characters of the Gymnospermae 

 and Angiospermae are as follows: 



