384 



BOTANY 



of the order. The flat, two-ranked leaves and slender scapes arise from a 

 rhizome. The pistillate flowers are crowded together at the lower part of the 

 thick spike, the staminate flowers being at the apex, later falling away from the 

 axis, which projects beyond the dark-brown fruit-spike. 



Fam. 2. Sparganiaceae. This family also consists of a single genus, Spar- 

 ganium, with six to eight species. S. eurycarpum, the Bur-reed, is the common 

 species of the Eastern United States. S. Greenii, a similar species, occurs 

 in California, and several other species occur within our territory, The flowers 

 are borne in globular heads, the pistillate below the staminate (Fig. 356). The 

 flowers have a rudimentary perianth. 



Fam. 3. Pandanacese. The Pandanacese, or Screw-pines, are tropical 

 plants of peculiar structure and doubtful affinities. The structure of the 

 flowers and fruit suggest the Sparganiacese, and they have been placed next 

 these, although they are sometimes supposed to be nearer the Palms. There are 

 two genera, Freycinetia, climbing plants especially abundant in the Malayan 

 regions, and Pandanus, mostly arborescent forms of wider distribution than 

 Freycinetia, but not found in the American tropics. A single species of each 

 genus is found in the Hawaiian Islands. 



They are characterized by narrow leaves, arranged upon the stem in a spiral 

 series, hence the name "Screw-pine." The stems branch freely, and show a 



secondary increase in thick- 

 ness like that of Yucca or Dra- 

 caena. The abundant aerial 

 roots are very characteristic, 

 and the ripe fruit-clusters in 

 some species look like a pine- 

 apple. 



Order III. Glumiflorae 



The Glumiflorse include the 

 Grasses (Graminese) and 

 Sedges (Carices), which are 

 probably not closely related. 

 The flowers in these plants are 

 destitute of a proper perianth, 

 and are protected by special 

 chaffy bracts (Glumes), which 

 give name to the order. 



In the Grasses the flowers 

 are usually hermaphrodite, but 

 may be diclinous, as in Indian- 

 corn. The typical flower of 

 the Grasses (Fig. 358) has a 

 single carpel, with a single 

 ovule and three stamens (some- 

 times two). Less often (Bam- 



busa) there are six stamens, and in some cases (Luziola sp.) there may be more. 



There are usually two plumose styles, which may be joined together, as in the 



Indian-corn, where each thread of the "silk" is composed of two united 



styles. 



The flowers of the Grasses are arranged in "Spikelets," which are enclosed 



by two glumes, each flower of a spikelet consisting of two bracts ("Palese"), 



-St 



lod 



FIG. 358. Dactylis glomerata. A, spikelet, en- 

 larged. B, single flower, showing lodicules, 

 lod, and the stigmas, st. C, stem with sheath- 

 ing leaf-base, showing ligule, I. 



