186 



PHYLUM TRACHEOPHYTA: 



forms, female cones are complex and unlike the sim- 

 ple cycad cones, but the male cones of both cycads 

 and conifers are similar; typical cones are absent in 

 the Taxales and Gnetales; certain forms, especially 

 the Coniferales, have special resin ducts and resin, a 

 character apparently shared only with the angio- 

 sperms. 



ORDER CONIFERALES (Conifers) 



Diagnosis: known from Lower Permian to Recent; 

 mostly trees in the form of well-known pines (Pinus), 

 larch (Larix), spruce (Picea), hemlocks (Tsuga), firs 

 {Abies), redwood {Sequoia), cypress {Cupressus), juniper 

 {Juniperus), plus distinctive Southern Hemisphere 

 forms like Bunya-Bunya, monkey puzzle, and Nor- 

 folk Island pine {Araucana) , certain Australian region 

 "pines" {Agathis), and the widely cultivated Southern 

 Hemisphere fern pines {Podocarpus); a few are shrubs; 

 trees with a distinctive central trunk and smaller lat- 

 eral branches (similar to most fossil forms) to 300 

 feet tall with bases 20 feet wide in redwoods; con- 

 siderable secondary tissue growth, producing growth 

 rings reflecting wet and dry seasons (annual rings can 

 be used to approximate past climate); leaves typically 

 needle-like or narrow (mostly less than X inch wide 

 and y-i inch to 6 inches long), but some are fairly 

 broad and almost have true parallel venation; some 



Figure 11.22 The moidenhoir tree, Ginkgo: A, fruiting branch; B, 

 female branch with two developing ovules; C, male branch or cone. 



Figure 11.23 Life cycle of a pine, Pinus: a., female sex organ; b., 

 cone scale; e., embryo; f.c, female cone; f.g., female gametophyte; m., 

 micropyle; m.c, male cone; ms., male sporangium in cone scale; o.s., 

 egg-bearing part of cone scale; p., pollen groin; s.c, seed coat; si., 

 seedling. (Used by permission, from Arthur Cronquist, Introductory 

 Botany, Harper, New York, 1961.) 



leaves are minute and scale-like, none are fan-shaped 

 as in ginkgos; leaf arrangement is normally alternate 

 in a close spiral, but both opposite and whorled ar- 

 rangements occur; various modified leaf arrange- 

 ments exist, some leaves are on specialized short 

 shoots and others are bound together at the base by 

 a membranous bundle sheath, or fascicle, that is 

 formed from leaves fusing; sporangia arranged in 

 male or female cones, diflfering from other living or- 

 ders by the presence of distinct cones; male cones 

 about J/4 inch to 4 inches long; female cones about 1 

 to 20 inches long; female cones typically woody 

 {Pinus) or at least parchment- like {Sequoia) in consis- 

 tency, but certain forms {Juniperus) are almost fleshy 

 and berry-like (Figure 11.24). 



Uccurrence: about 300 living species, mostly in 

 temperate and cold temperate climates but occurring 

 from Arctic to Antarctic Circles; represent remnants 

 of a once much larger group. 



