1915] 



BESSEY — PHYLOGENETIC TAXONOMY 117 



dicarpellate orders Gentianales, Polemoniales, Scrophulariales 

 and Lamiales, constituting a series which shows diminishing 

 numbers of stamens, carpels and seeds, and increasing 

 zygomorphy. This phyletic sequence from Randies to Lami- 

 ales constitutes the sub-class Strobiloideae, or cone-flowers. 



Beturning again to the Ranales, we find that they give rise 

 to the simpler, cotyloid, apopetalous, polystemonous, poly- 

 carpous, hypogynous Rosales (sub-class Cotyloideae), from 

 which by the early deepening of the cotyloid structure we have 

 the mostly polystemonous, polycarpous, epigynous Myrtales, 

 Loasales and Cactales as a strongly developed side line. The 

 oligostemonous Celastrales continue the main phyletic line 

 with reducing numbers of stamens, carpels and seeds, and a 

 gradual deepening of the cup, to the side-line of the Sapin- 

 dales, which are eventually epigynous, and the mostly dicar- 

 pellate Umbellales. The sympetalous, epigynous Rubiales 

 with reduced calyx, few carpels and few seeds, pass easily into 

 the C ampanulales , and the Asterales, the latter with but one 

 seed in the dicarpellary, one-celled, one-seeded, inferior ovary, 

 and with its calyx, when not obsolete, transformed into bracts, 

 spines or bristles to form a ' ' pappus ' ' for the efficient distribu- 

 tion of the seeds. 



II. Taxonomy of Flowering Plants 



Phylum XIV. ANTHOPHYTA. The Flowering Plants. 



Typically chlorophyll-green plants ( a few colorless hystero- 

 phytes), ranging from small or even minute plants to great 

 trees a hundred or more meters in height ; alternation of gen- 

 erations obscured by the extreme reduction of the gameto- 

 phyte to a condition of dependence upon the long-lived, leafy- 

 stemmed sporophyte. Spores of two kinds (heterosporous), 

 produced on sporophylls which are borne in modified, often 

 much reduced strobili (flowers) ; microsporophylls (stamens) 

 normally with four sporangia (pollen sacs) ; the microspores 

 being set free (as " pollen") when mature; megasporophylls 

 (carpels) folded lengthwise (constituting the " pistil") en- 

 closing the sporangia (ovules) in which the megaspores 



