二、单子叶植物纲
二、单子叶植物纲
基本特征胚具1顶生子叶。茎内维管束散生，无形成层，通常不能加粗）叶脉通常是平行脉或弧形脉，花的各部通常为3或其倍数。外轮或内轮花被通常形似。，主根不发达，须根系。2
2 基本特征 • 胚具 1 顶生子叶。 • 茎内维管束散生，无形成层，通常不能加粗。 • 叶脉通常是平行脉或弧形脉。 • 花的各部通常为 3 或其倍数。外轮或内轮 花被通常形似。 • 主根不发达，须根系
DICOTMONOCOTSingleTwOCotyiedonCobyledonLongBroad LearNarrowLearNetworkofVeinsParallelVeinsVascularVascuarBundlesBundlesScatteredinaRingFloralFloralParts inParts inMultiplesMultipiesof3of4or53
3
·5亚纲，19目，65科，50000余种。AmborellalesbasalangiospermsNymphaealesAustrobaileyalesmagnolidsangiospermsChloranthalesmonocotscoreangiospermsCeratophyllaleseudicots4
• 5亚纲，19目，65科，50000余种。 4
Cladogram2:Thephylogeneticcompositionofthemonocots[78]AcoralesAlismatid monocotsAlismatalesPetrosavialesDioscoreales115120Lilioid monocotsPandanales91monocots131Liliales121122Asparagales120Arecales121Poalescommelinids118ZingiberalesCommelinalesOfsome70,000species,901byfarthelargestnumber(65%arefoundintwofamiliestheorchids andgrasses.Theorchids(Orchidaceae,Asparagales)containabout25,000speciesandthegrasses(Poaceae,Poales)about11,ooo.OtherwellknowngroupswithinthePoalesorderincludetheCyperaceae(sedges)andJuncaceae(rushes),andthemonocots also includefamiliarfamilies suchasthepalms(Arecaceae.Arecales)and5lilies(Liliaceae,Liliales)
5 Of some 70,000 species,[90] by far the largest number (65%) are found in two families, the orchids and grasses. The orchids (Orchidaceae, Asparagales) contain about 25,000 species and the grasses (Poaceae, Poales) about 11,000. Other well known groups within the Poales order include the Cyperaceae (sedges) and Juncaceae (rushes), and the monocots also include familiar families such as the palms (Arecaceae, Arecales) and lilies (Liliaceae, Liliales)