98 THE FLOUAL ENVELOPS, OR PERIANTH. 



ing to the law of alternation of organs ; two sepals arc united in the 

 lower lip and three in the upper, as seen in the sage and the Labiate 

 Order generally. Labiate flowers arc said to be galeate or helmeted 

 when the upper lip is concave, as in catmint ; ringent or gaping when 

 the throat or mouth is wide open ; personate or masked when the throat 

 is closed as with a palate, like the snapdragon. 



484. ORCHIDACEOUS, a form of the perianth peculiar to the Orchis 

 with that large and singular tribe in general. It is a 6-parted double 

 perianth, very irregular, characterized chiefly by its lip (labellum), 

 which is the upper petal (lower by the twisting of* the ovary) enlarged 

 and variously deformed. 



Certain reduced forms of the perianth require notice here : 



485. PAPPUS (TraTTTOf, grandfather, alluding to his gray hairs) is a 

 term applied to the hair-like calyx of the florets of the Composite and 

 other kindred orders. The florets of this order arc collected into 

 heads so compactly that the calyxes have not room for expansion in 

 the ordinary way. The pappus is commonly persistent and often in- 

 creases as the fruit matures, forming a feathery sail to waft away the 

 seed through the air, as in the dandelion and thistle. It varies greatly 

 in form and size, as seen in the cuts, sometimes consisting^ of scales, 

 sometimes of hairs, again of feathers or bristles. Sometimes it is 

 mounted on a stipe, which is the beak of the fruit. 



332 



Cypsela (incorrectly called achenium) of the Composite, with various forms of pappus. 328, 

 Eclipta prorumbens, no pappus. 329, Ambrosia trifida. 330,IIelianthus grosse-serratus, pappus 

 2-awned. 331, Ageratum conizoides, pappus of five scales. 332, Mulgedium, capillary pappus 

 cypsela slightly rostrate. 333, Lactuca elongata, rostrate cypsela. 



486. OTHER REDUCTIONS. Again, the calyx or the limb of the calyx 

 is reduced to a mere rim, as seen in the Umbellifcrae. In the amenta- 

 ceous orders the whole perianth diminishes to a shallow cup, as in the 

 poplar, willow, or altogether disappears, as in the birch, ash, lizard-tail. 

 (204-287). 



487. SET^E, meaning bristles in general, is a term specifically used to 

 denote the reduced perianth of the sedges. In the bog-rush (Scirpus) 

 there is, outside the stamens, a circle of six setae, which doubtless rep- 

 resent a 6-leaved perianth. In the cotton-grass (Eriphorum) the setae are 

 multiplied and persistent on the fruit, becoming long and cotton-like. 



