链型植物下界

在传统生物分类学上，轮藻门为并系群，泛指排除了有胚植物后剩下的所有链型植物；但在目前推广的支序系统学定义下，有胚植物被归属于轮藻门下，轮藻门则被升级改为单系群，因此链型植物与（新定义的）轮藻门同义，下属包括中斑藻纲（Mesostigmatophyceae）、绿方藻纲（Chlorokybophyceae）、链丝藻纲（Klebsormidiophyceae）和膜生植物（Phragmoplastophyta）四个演化支。有胚植物则演化自膜生植物，与轮藻纲（Charophyceae）、鞘毛藻纲（Coleochaetophyceae）和双星藻纲（Zygnematophyceae）互为姐妹群。

Streptophyta , informally the streptophytes (, from the Greek strepto 'twisted', for the morphology of the sperm of some members), is a clade of plants. The composition of the clade varies considerably between authors, but the definition employed here includes land plants and all green algae except the Chlorophyta and the more basal Prasinodermophyta.

Classifications

The composition of Streptophyta and similar groups (Streptophytina, Charophyta) varies in each classification. Some authors include only the Charales and Embryophyta (e.g., Streptophyta, Streptophytina); others include more groups (e.g., Charophyta, Streptophyta, Streptobionta); some authors use this broader definition, but exclude the Embryophyta (e.g., Charophyta, Charophyceae, Streptophycophytes).

The clade Streptophyta includes both unicellular and multicellular organisms. Streptophyta contains the freshwater charophyte green algae and all land plants that reproduce sexually by conjugation. Mesostigma viride, a unicellular green flagellate alga may be a basal Streptophyte.

These earlier classifications have not taken into account that the Coleochaetophyceae and the Zygnemophyceae appear to have emerged in the Charophyceae + Embryophyta clade, resulting in the synonymy of the Phragmoplastophyta and Streptophytina/Streptophyta sensu stricto (a.k.a. Adl et al., 2012) nomenclature.

Jeffrey, 1967

• Streptophyta
• Charales
• Embryophyta

Lewis & McCourt 2004

• Division Charophyta (charophyte algae and embryophytes)
• Class Mesostigmatophyceae (mesostigmatophytes)
• Class Chlorokybophyceae (chlorokybophytes)
• Class Klebsormidiophyceae (klebsormidiophytes)
• Class Zygnemophyceae (conjugates)
• Order Zygnematales (filamentous conjugates and saccoderm desmids)
• Order Desmidiales (placoderm desmids)
• Class Coleochaetophyceae (coleochaetophytes)
• Order Coleochaetales
• Subdivision Streptophytina
• Class Charophyceae (same as the Smith system, 1938)
• Order Charales (charophytes sensu stricto)
• Class Embryophyceae (embryophytes)

Leliaert et al. 2012

• Streptophyta
• charophytes
• Mesostigmatophyceae
• Chlorokybophyceae
• Klebsormidiophyceae
• Charophyceae
• Zygnematophyceae
• Coleochaetophyceae
• Embryophyta (land plants)

Adl et al. 2012

• Source:
• Archaeplastida Adl et al. 2005
• Chloroplastida Adl et al. 2005 (Viridiplantae Cavalier-Smith 1981)
• Chlorophyta Pascher 1914, emend. Lewis & McCourt 2004

Charophyta Migula 1897, emend. Karol et al. 2009 (Charophyceae Smith 1938, Mattox & Stewart 1984)

• Chlorokybus Geitler 1942
• Mesostigma Lauterborn 1894
• Klebsormidiophyceae van den Hoek et al. 1995
• Phragmoplastophyta Lecointre & Guyander 2006
• Zygnematophyceae van den Hoek et al. 1995, emend. Hall et al. 2009
• Coleochaetophyceae Jeffrey 1982
• Streptophyta Jeffrey 1967

Charophyceae Smith 1938, emend. Karol et al. 2009 (Charales Lindley 1836; Charophytae Engler 1887)

Embryophyta Engler 1886, emend. Lewis & McCourt 2004 (Cormophyta Endlicher 1836; Plantae Haeckel 1866)

Adl et al. 2019

• Source:
• Archaeplastida Adl et al. 2005
• Chloroplastida Adl et al. 2005 (Viridiplantae Cavalier-Smith 1981)
• Phylum Streptophyta [Charophyta]
• Chlorokybus atmophyticus
• Mesostigma viride
• Family Klebsormidiophyceae
• Class Phragmoplastophyta
• Family Zygnemataceae
• Order Coleochaetophyceae
• Family Characeae
• Kingdom Embryophyta

Phylogeny

Below is a reconstruction of Streptophyta relationships, based on genomic data.

Streptofilum, described in 2018, appears to bring in a new branching.