FLORIN: SYSTEMATICS OF THE GYMNOSPERMS 37I 



sification of the vascular plants in cryptogams and phanerogams, and in pterido- 

 phytes, gymnosperms, and angiosperms is not natural. It is horizontal in charac- 

 ter, and records different levels or ])hases of general organization instead of ex- 

 pressing natural relationships. We have thus arrived at a point where the term 

 Gymnospermae of the nineteenth century is often regarded as obsolete, and 

 therefore abandoned. According to an extreme view, each of the main groups of 

 gymnosperms represents a separate evolutionary line (P. Bertrand, 1947; Ber- 

 trand and Corsin, 1938). According to Halle (1937) the evolution of the seed- 

 plants has probably, since an early date, proceeded along at least two divergent 

 main lines, viz., one in which the seeds and sporangia became localized to leaves 

 of the megaphyllous type, and another in which the plant body was differentiated 

 into a vegetative and a reproductive region, the spore-producing members con- 

 gregating to form "inflorescences" or "flowers," and the terminal position of 

 the ovules and sporangia retained for a long time. The cordaites, appearing 

 early in the history of the liigher plants, represent an offshoot of this second 

 series. In Arnold's (1948) opinion the gymnosperms {minus tlie chlamydo- 

 sperms) are composed of two separate groups of high rank, the cycadophytes 

 and the coniferophytes, distinguished by features that have characterized them 

 as far back as they can be traced. Contrary to Ilalle, Arnold referred both cy- 

 cads and cycadeoids to the cycadophytic line. As mentioned earlier, Sahni 

 (1920, 1948) divided the gymnosperms into phyllosperms and stachyosperms, 

 but Schoute (1925) and Eames (1952) did not think this measure justified. 

 Lam (1948, 1952), however, extended Sahni's idea of the discrimination between 

 phyllosperms and stachyosperms within the Gymnospermae to comprise all vas- 

 cular plants of both sexes, and regarded stachyospory and phyllospory as im- 

 portant factors in the system of the cormophytes. Phyllospory, or the position 

 of the sporangia on many-telomed sterile fronds, i.e., true sporophylls, is re- 

 garded as the advanced condition, and stachyospory — where the sporangia, ori- 

 ginally axis-borne, are not, or hardly at all, connected with sterile telomes or 

 syntelomes except by secondary processes — as the primitive feature. There are 

 strictly stachyosporous and fully phyllosporous groups of plants, but also groups 

 of a mixed nature. Lam's views, too, have been negatively criticized by Tak- 

 htadjan (1950) and Eames (1951), but he maintains them even in his latest 

 publications. 



Turning now to particulars of the more recently propounded systems ( Schaff- 

 ner, 1934; Wettstein, 1935; Engler and Diels, 1936; Pulle, 1937, 1950; Skotts- 

 berg, 1940; Tippo, 1942; Gaussen, 1944-1952; Arnold, 1948; Lam, 1948; Em- 

 berger, 1949, 1952b; Chadefaud, 1949; Johansen, 1950, 1951; 'Nemejc, 1950; 

 Takhtadjan, 1950; Florin in H. Erdtman, 1952; McLean and Ivimey-Cook, 1951; 

 Rothmaler, 1951, 1951-1952; Neger, Miinch and Huber, 1952; cf. Florin, 1952b), 

 it is, as already indicated, a striking feature of some of them that the traditional 

 taxon Gymnospermae has been either discarded, or its circumscription altered. 

 The presence of naked seeds (or ovules) is an attribute which has begun to lose 

 prominence. In Lam's system, which divides the Cormophyta into four main 

 groups on the grounds of morphology and phylogeny, the Gymnospermae (ex- 

 cept the pteridosperms and chlamydosperms) are called Mesocormophyta. Em- 

 phasizing a presumed polyphyletism of the Gymnospermae (in the old sense), 

 Arnold proposes to substitute for this division three independent groups of 



