278 MORPHOLOGY 



The preceding alliances are the so-called spiral alliances, in which 

 the floral members are not definitely and constantly of the same num- 

 ber. While the floral number three is a feature of monocotyledons, it 

 is evident that it does not apply to the spiral alliances in the same sense 

 that it does to the cyclic alliances. 



In the following cyclic alliances the almost constant floral formula is: 

 perianth 3 + 3, stamens 3+3, carpels 3 (and syncarpous). Further- 

 more, the perianth is the conspicuous floral feature rather than bracts, 

 and insect pollination is well established. In other words, the real 

 flowers of monocotyledons, as ordinarily recognized, belong to the 

 cyclic alliances. 



7. Farinales (n families, 2000 species). This alliance is in a certain 

 sense a transition group between the spiral and cyclic alliances; for al- 

 though the cyclic number is established, many of the forms are grass- 

 like herbs with bractlike perianth, as in the rushes (Juncaceae); but 

 there are also forms with showy corolla, as the spiderwort (Tradescantia) . 



8. Liliales (9 families, 5000 species). These may be regarded as 

 the representative monocotyledons, with conspicuous and usually regular 

 perianth, and well-established insect pollination. Most of the mono- 

 cotyledonous flowers of ordinary experience belong here. The group 

 shows a distinct development from hypogyny, as in the amaryllises 

 (Amaryllidaceae), to epigyny, as in the flags (Iridaceae). 



The two remaining cyclic alliances are characterized not only by 

 epigyny, but also by the extreme irregularity of the flowers. 



9. Scitaminales (4 families, 800 species). These are the cannas, 

 bananas, and gingers of the tropics. One peculiar feature of the group is 

 the so-called false stem, which may be seen in the banana. The stem- 

 like structure, which often rises to a considerable height, is built up of the 

 heavy and overlapping bases of the leaves. 



10. Orchidales (2 families, 7000 species). The orchids are notable 

 for the great irregularity and showiness of their flowers, and for their ex- 

 treme specialization in insect pollination. The number of species runs 

 very high, but orchids cannot be regarded as abundant. By contrast- 

 ing the 7000 species of grasses and sedges with the 7000 species of 

 orchids, it becomes evident that although the species of two groups may 

 number the same, the number of individuals may be very different. 

 The orchids may be regarded as the culmination of monocotyledons 

 in floral structure, and that culmination is expressed by epigyny and 

 extreme irregularity. 



