50 Charles E. Bcsscy 



gametophyte tissue (endosperm), embedded in the i- or 2-coated 

 sporangium, constitutes the seed. Sporophyte stems with col- 

 lateral fibrovascular bundles in a circular row, and increasing in 

 diameter by a cambial zone. 



In this phylum the primitive seed-bearing strobilus of the Tax- 

 odiaccae became more complex in the line of development through 

 Araucariaccae to Abictaceae, while it became simpler and smaller 

 in the line through Cnpressaccae, to Podocarpaceae and Taxaccac. 



Class 33. PINOIDEAE. With the characters of the phylum. 



Order Coniferales. Both microsporophylls and megasporo- 

 phylls in strobili, usually monoecious. 



Family i. Taxodiaceae, Large to very large trees, mostly 

 evergreen ; each microsporophyil with 2 to 8 sporangia ; each 

 megasporophyll eventually woody, ^vith 2 to 8 axillary and erect 

 sporangia (seeds), or superficial and inverted; trees, monoecious. 

 Sequoia, Arthrotaxis, Taxodiiini. (Pf. II, i, 84.) This is a very 

 old family, most living genera having fossil representatives, which 

 in some cases lived as long ago as the Coal Period. In addition 

 to these, many genera which formerly existed have become wholly 

 extinct. 



Family 2. Araucariaceae. Large trees of the southern hem- 

 isphere, all evergreen; each microSporophyll with 5 to 15 spor- 

 angia ; each megasporophyll, eventually woody, with one inverted 

 sporangium (seed) ; "seed scale" rudimentary or wanting; trees 

 mostly dioecious. Agathis, Araucaria. (Pf. II, i, 66.) Many 

 fossil species of the two living genera are known, and in addition 

 some fossils have been referred to genera now extinct. 



Family 3. Abietaceae. Large trees of both hemispheres, 

 mostly evergreen ; each microsporophyil with two sporangia ; 

 each megasporophyll develops a woody ''seed scale" which bears 

 two inverted sporangia (seeds) ; trees monoecious. Finus, Larix, 

 Picea, Abies. (Pf. II, i, 69.) Many fossil species of most of 

 the living genera are known from the later geological periods. 



Family 4. Cupressaceae. Large evergreen trees of the north- 

 ern hemisphere ; each microsporophyil with 4 to 8 sporangia ; 

 each megasporophyll shield-shaped, woody, bearing one to many 

 sporangia (seeds) ; no "seed scale"; trees, monoecious. Ciiprcs- 



324 



