38 



STRUCTURAL BOTANY. 



the Poplar and Willow, or altogether disappears, as in the Birch. 

 Ash, and Lizard-tail (15, 16). 



106. Seta?, meaning bristles in general, is a term specifically 

 xised to denote the reduced perianth of the sedges. In the Bog- 

 rush (Scirpus) there is, outside the stamens, a circle of six setae, 

 representing a 6-leaved perianth (78). In the Cotton-grass 

 (Eriphorum) the setae are multiplied and persistent on the fruit, 

 becoming long and cotton-like. 



107. Perigynium is the name given to the urceolate perianth 

 of Carex, investing the ovary but 



allowing the style to issue at its sum- 

 mit. It is composed of two united 

 sepals, as indicated by the two teeth 

 at the top (79). 



108. Glumes and pales repre- 

 sent the floral envelopes, or rather 

 the involucre of the Grasses (436). 

 Their alternating arrangement clearly 

 distinguishes them from a perianth. 



109. The duration of the calyx 

 and corolla varies widely, and is 

 marked by certain general terms. 

 It is caducous when it falls oft* im- 

 mediately, as the calyx of Poppy, 



corolla of Grape ; deciduous when it falls with the stamens, as 

 n most plants ; and persistent, if it remain until the fruit ripens, 

 as the calyx of Apple. If it continue to grow after flowering, it 

 is accrescent and if it wither without falling off, it is marescent. 



Review.- 99. Primary distinctions in the forms of the perianth. 100. Four forms of 

 nolypetalous-regnlar perianths. To which belongs Stock? Pink? Apple? Lily? 101. 

 Two forms of polypetalous-irregular describe. Explain figs. 59-61. 102. Name the 

 seven forms of gamopetalous-regular. To which belongs fig. 62? 63? 64? 65? etc. The 

 flowers of Elder? Kalmia? Harebell? 103. Describe the gamopetalous-irregular foima, 

 etc. 104. What is pappus ? Describe the figures 72-77. 106. Perianth of Bog-rush 107. 

 Of Carex 108. Of Grasses. Point out the glumes The pales. 109. Define caducous 

 Deciduous Accrescent Marescent. 



78 



78, Flower of Scirpus lacustris, magni- 

 fied; consisting of six seta>, three stamens, 

 three pistils united, except the stigmas. 

 79, Flower of Carex rivularis 9 . with </, 

 its glume, p, its bottle-shaped perigynium, 

 2-toothed at top, enveloping the tripU 

 ovary; stigmas, three. 



