DICOTYLEDONS 301 



spiral arrangement), and study a flower with its tri- or bi- 

 stigmatic pistil, three stamens and (usually) six perianth bris- 

 tles. Cyperus differs mainl}- in its two-ranked spikelets, and 

 absence of perianth bristles. 



(j) Study an AmarylUs flower in longitudinal and cross- 

 sections as in the lily (c). The small, somewhat zygomorphic 

 flowers of the banana (Musa) may be substituted for the amar- 

 yllis. Note the absence of one stamen. Study also the ma- 

 ture fruit (usually seedless) in sections. 



(k) Make a similar study of the Iris flower. 



(l) For Orchids the Lady's Slipper (Cj^pripedium) should be 

 studied, and its two stamens grown fast to the tristigmatic 

 style, one petal slipper-shaped (''lip"), the other two much 

 like the pointed, rather elongated sepals (two of which are often 

 united). Note the sticky pollen, and the very numerous, mi- 

 nute seeds. For this may be substituted the native Orchis, or 

 Ibidium, or various greenhouse orchids; here the single stamen 

 is attached to the bistigmatic style, and the petals and sepals 

 are very variable, one petal ("lip") being always much longer 

 and more showy. 



CLASS DICOTYLEDONEAE. 



The Dicotyledons 



547. Cotyledons two; leaves opposite on the stem, 

 later ones opposite or alternate; vascular bundles in 

 the stem arranged cylindrically (in a ring 

 as seen in cross-section) ; vascular bundles 

 in the leaf-blades irregularly netted 

 C'netted-veined"); perianth whorls 

 mostly quinate (in 5's). 



548. There are two greater types (sub- grams oV ' flower 

 classes) of Dicotyledons, which are dis- 

 tinguished by the structure of the flower axis, as follows: 



1. Flower axis cyHndrical, spherical, hemispherical or flat- 

 tened, bearing on its surface the flower parts (perianth, stamens 

 and carpels) "Axis Flowers" (Axiflorae). 



2. Flower axis more or less expanded into a disk or cup, 



