PINACEAE. Trees and shrubs, usually monoecious. Male cones like those of Podocarpaceae, with two pollen sacs to each sporophyll. Female cone compact with many pairs of scales, the upper of each pair bearing two, or rarely more, ovules. Archegonia separate, each in its own jacket cells, as in Podocarpaceae.
A. Pollen with no prothallial cells. A single grooved leaf on each short shoot with two veins, one either side of the groove. Several ovules on the ovuliferous scale_ Tribe i. Sciadopitoideae. Sciadopitys. Except for the separate archegonia, could be equally well placed in the Cupressaceae.
B. Pollen with two ephemeral prothallial cells. Leaves with a single vein. Two ovules on each ovuliferous scale. Tribe 2. Abietoideae.
(i.) Leaves almost entirely borne on spur shoots.
*From one to five leaves (the number more or less constant in each species) on each short shoot. Pinus.
**A tuft of more than five leaves on each spur shoot.
tLeaves not deciduous. Cedrus.
t tLeaves deciduous.
°Cone scales deciduous. Rim of micro pyle spreading. Pollen winged. Pscu dolay ix.
coCone scales persistent. Rim of micro pyle infolded. Pollen not winged. Larix.
(ii.) Leaves borne on branches of unlimited growth.
*Bract scales three-lobed, and projecting beyond the ovuliferous scales. Rim of the micropyle infolded. Pscudotsuga.
`*Bract scales not three-lobed even when longer than the ovuliferous scales. Rim of the micro pyle spreading.
t Cones pendulous. Cone scales persistent.
°Pollen sacs dehisce longitudinally.
Pollen winged. Cones large. Picea.
°OPollen sacs dehisce transversely.
Pollen globose. Cones small. Tsuga. uCones erect. Cone scales deciduous. Bract scales often longer than the ovuliferous scales. Leaves flat. Abies.
IV. CUPRESSACEAE. Trees or shrubs, often dioecious. Only one kind of scale in the female cone as a rule, but sometimes with outgrowths on the upper surface. Number of fertile scales usually much smaller than in Pinaceae, often only from two to six or eight. Ovules inverted or more often erect, commonly more than two to each fertile scale. Archegonia in one or more groups, not solitary. Male cones small with usually three or more pollen sacs to each sporophyll. Pollen grain without prothallial cells. Leaves usually small, not infrequently dimorphic, as in Juniperus chinensis.
A. Leaves opposite or whorled. Ovules erect.
(i.) Archegonia in a single apical group. Tribe I. Cupressoideae.
*Cone scales ripening fleshy. Juniperus. **Cone scales ripening woody.
t Cone scales peltate. Cupressus.
1- t Cone scales not peltate.
°Cone scales imbricate.
a. Four or five seeds to each scale. Thujopsis.
/3. Usually two seeds to each scale.
§Two fertile scales. Libocedrus.
§§Four fertile scales. Thuja. c°Cone scales valvate. Tetraclinis.
(ii.) Archegonia never apical, but in one or more ' lateral groups, usually deep-seated. Tribe 2. Callitroideae.
*Scales slightly imbricate (imperfectly known; may prove to belong to the preceding tribe). Fitzroya.
**Scales valvate.
t Fertile scales four in decussate pairs. Widdringtonia.
iFertile scales six in alternating whorls of three.
with a number of sterile bracts at the base. Fertile scales all equal. Actinostrobus.
sterile bracts at base of cone. Fertile scales unequal. Callitris.
(i.) Archegonia in a single apical complex. Tribe 3. Taxodioideae.
`Leafy branchlets deciduous. Taxodium. **Leaves, cone-scales deciduous. Glyptostrobus. ***Neither leaves nor branchlets deciduous.
t Seeds erect. Cryptomeria.
ttSeeds inverted.
°Fertile scales with a narrow transverse membrane (ligule) above the seed. Leaves lanceolate. Cunninghamia.
°°Fertile scales with a transverse ridge above the seed. Athrotaxis.
(ii.) Archegonia never apical. Tribe 4. Sequoideae. Sequoia.
It is quite possible that tribes 3 and 4 above should be merged in tribes I and 2 respectively, the distinction based on the leaf arrangement being` probably unimportant, and not always con stant.
V. TAXACEAE. Small trees and shrubs, usually dioecious, with much reduced female cones often consisting of single naked erect ovules subtended by a number of bracts, the ovules usually with an outer fleshy integument. Arche gonia as in Pinaceae. Male cones small with peltate or crested sporophylls each bearing from two to seven, or more pollen sacs. Pollen grains without prothallial cells. Leaves usually free and blade-like.
*One or two erect ovules borne on a small fleshy fertile scale which becomes abortive as the seeds ripen. No aril. Cephalotaxus.
**" Cone " reduced to a naked ovule. Aril present. fMicrosporophylls crested, with two to four pollen sacs. Torreya.
j' fMicrosporophylls peltate with four to eight pollen sacs. Taxus.