裸子植物门
1.常绿，木本；茎干圆柱状，不分枝；木质部具管胞；叶螺旋状排列；雌雄异株，雄球花顶生·························································Ι.苏铁科Cycadaceae 2.乔木，茎不分枝；具宿存叶痕；羽状叶集生于干顶，裂片条形，缘向外反卷；种子熟时橘红色，倒卵状或长圆状，疏被绒毛·····························1.苏铁Cycas revolute 1.落叶乔木；枝分长枝与短枝。叶扇形，有长柄，具多数叉状并列细脉，在长枝上螺旋状排列散生，在短枝上成簇生状。球花单性，雌雄异株·················Ⅱ.银杏科Ginkgo 2.树皮灰褐色，深纵裂；幼年及壮年树冠圆锥形；大枝近轮生，柔荑花序·············· ··························································2.银杏Ginkgo biloba 1.常绿乔木，皮层具树脂。叶螺旋状着生或交叉对生。球花单性，雌雄异株或同株；苞鳞木质或厚革质，种子与苞鳞离生或合生，扁平，无翅或两侧具翅，或顶端具翅············ ·······················································Ⅲ.南洋杉科Araucariaceae 2.常绿大乔木，树冠塔形，层次分明，主枝轮生；球果卵形或椭圆形翅果············ ·················································3.南洋杉Araucaria cunninghamii 1.常绿或落叶乔木，稀为灌木状；枝仅有长枝，或兼有长枝与生长缓慢的短枝，短枝通常明显，稀极度退化而不明显。花单性，雌雄同株························Ⅳ.松科Pinaceae 2.叶条形或四棱形，仅长枝，无短枝····························冷杉亚科Abietoideae
3.球果成熟后种鳞自宿存中轴上脱落，球果腋生，直立；叶扁平········冷杉属Abies 4.一年生枝淡灰黄色或淡黄褐色，无毛；球果圆柱形；苞鳞短，不外露············ ················································4.辽东冷杉Abies holophylla 3.种鳞宿存，球果顶生，通常下垂，叶在枝条上均匀排列；叶四棱形或扁平棱形；小枝有极显著隆起的叶枕，四面有气孔线·······························云杉属Picea 4.基部宿存芽鳞向外反曲，幼时气孔带明显，灰白色，叶先端尖或锐尖 5.一年生小枝无白粉，球果种鳞露出部平滑无纵纹········5.红皮云杉P.koraiensis 4.叶先端钝，小枝无白粉······································6.白杄P.meyeri 4.小枝灰白色，顶芽卵圆形；基部宿存芽鳞不反曲，叶扁四棱形，幼嫩叶绿色···· ··························································7.青杄P.wilsonii 4.二年生枝淡粉红色，常被白粉；叶为四棱锥形，先端钝·······8.青海云杉P.crassifolia 2.有长短枝之分，叶条形或针形，叶在长枝上螺旋状互生，短枝上簇生；种鳞扁平；球果当年成熟················································落叶松亚科Laricoideae 3.落叶乔木，球果直立，种鳞革质，宿存；种子上部有膜质长翅·················· ·····························································落叶松属Larix 4.种鳞上部边缘不反曲或微反曲；一年生枝色浅，无白粉······················ ··········································9.华北落叶松L.principis-ruprechtii 4.种鳞上部边缘显著向外反曲；一年生枝红褐色，被白粉························ ··················································10.日本落叶松L.kaempferi
3. 落叶乔木；枝有长枝与短枝；叶条形，球花生于短枝顶端；雄球花穗状，多数簇生，有细梗，雄蕊多数，螺旋状着生；球果当年成熟，直立，有短梗；种鳞木质·········· ·························································金钱松属Pseudolarix
4.落叶乔木，树皮灰褐色，叶下面中脉两侧各有一条气孔带····11.金钱松P.amabilis 3.常绿乔木，具长枝与短枝，叶三棱针形；雌雄球花分别单生于短枝顶端··········· ······························································雪松属Cedrus 4.树皮深灰色，不规则鳞片状剥裂；树冠尖塔形，雌雄异株，球果成熟后脱落···· ··························································12.雪松C.deodara
2.枝具特化短枝，叶针形，2.3.5针一束；种鳞盾形··················松亚科Pinoideae
3.叶鞘早落，；针叶3~5针一束；鳞脐顶生，稀背生·····················松属Pinus 4.叶3针一束；球果卵圆形，形小，鳞脐背生，有刺；树皮灰白色················ ·······················································13.白皮松P.bungeana 4.叶5针一束，球果圆锥形，鳞脐顶生，无刺；树皮灰色或灰褐色。
5.球果成熟时种鳞不张开或微张开，先端反曲；小枝密被黄褐色或红褐色绒毛···· ······················································14.红松P.koraiensis 5. 球果成熟时种鳞张开，先端不反曲，小枝绿或灰绿色，无毛················ ·····················································15.华山松P.armandii
3.叶鞘宿存；针叶2~3针一束，鳞脐背生，树皮灰褐或红褐色 4.叶长10cm以上，鳞脐有刺······························16.油松P.tabuliformis 4.叶短，长扭曲·····························17.樟子松P.sylvestris var.mongolica 1. 常绿或落叶乔木。叶螺旋状排列，披针形、钻形、鳞状或条形，球花单性，雌雄同株，球果当年成熟，熟时张开，螺旋状着生或交叉对生（水杉属），宿存或熟后逐渐脱落······ ······························································Ⅴ杉科Taxodiaceae 2.叶常绿，革质；叶被针形，叶缘具细齿；球果苞鳞发达，种鳞退化；中脉两侧各有一条粉白色气孔带·······································18.杉木Cunninghamia lanceolata 2.落叶乔木，幼树树冠尖塔形，老树广圆形；树皮灰褐色，长条状剥裂；雄球花于秋季形 成，总状或圆锥花序；球果矩圆状球形·············19.水杉Metasequoia glyptostroboides 1.成熟球果的种鳞木质或近革质，熟时张开；种子有翅，稀无翅······Ⅵ柏科Cupressaceae 2.种鳞扁平或鳞背隆起，但不为盾形；球果当年成熟。
3.种鳞4~6对，木质，背部有一弯曲的钩状剪头；种子无翅·······侧柏属Platycladus 4.球花单生枝顶；种子长卵形·······························20.侧柏P.orientalis 3.种鳞4对，革质，顶端具突起小尖头；种子两侧具翅················崖栢属Thuja 4.鳞叶先端尖，种鳞常5对····························21.北美香栢T.occidentalis 2.种鳞木质，盾形；球果当年或翌年成熟
3.生鳞叶的小枝不排列成平面，稀排成平面；球果翌年成熟········栢木属Cupressus 4.树皮淡灰褐色；鳞叶先端锐尖；球果近球形·················22.柏木C.funebris 2.成熟球果的种鳞肉质，成浆果状，熟时不张开或微张开；种子无翅················· ······························································刺柏属Juniperus
3.叶全为刺叶或鳞叶，或二者兼有，刺叶基部无关节，下延生长；冬芽不显著；球花单生枝顶。
4.植株具二型叶；鳞形和刺形，或幼树仅具刺形叶。 5.乔木，球果球形，每果具种子2~3························23.圆栢J.chainenisis 5.匍匐灌木，球果倒卵圆形，每果具种子3~5············24.叉子圆栢J.vulgaris 3.叶全为刺形叶，基部具关节；冬芽显著；球花单生叶腋。每果具3枚种子
4.叶钻状，先端锐尖，叶背面具明显的纵脊，内有1条白色气孔带。球果熟时蓝黑
色·······················································25.杜松J.regida 4.叶条状或被针状，纵脊不明显，具两条白色气孔带，先端汇合；球果熟时淡红色 或红褐色···············································26.刺柏J.formosana