Summary of Equisetum Taxonomy

Equisetum

Subgenus Equisetum (Hauke, in Nova Hedwigia, 1978)

Section Equisetum

fluviatile
palustre
bogotense
diffusum
telmateia

subspecies braunii

Section Heterophyadica

arvense
sylvaticum
pratense

Subgenus Hippochaete (Hauke, in Nova Hedwigia, 1963)

Section Incunabula

giganteum

Section Ambigua

ramosissimum

subspecies debile

myriochaetum
laevigatum

Section Hippochaete

Subsection Perennantia

hyemale

varietas affine

Subsection Homocormia

variegatum

varietas alaskanum

scirpoides

Subgenus Equisetum hybrids:

x dubium (arvense x telmateia)
x dycei (fluviatile x palustre)*1
x font-queri (palustre x telmateia)
x litorale (arvense x fluviatile)
x mildeanum (pratense x sylvaticum)
x rothmaleri (arvense x palustre)
x suecicum (arvense x pratense)
x wallichianum (arvense x diffusum)

Subgenus Hippochaete hybrids:

(hyemale x myriochaetum)
x ferrissii (hyemale x laevigatum)
x meridionale (ramosissimum x variegatum)
x moorei (hyemale x ramosissimum)
x nelsonii (laevigatum x variegatum)
x schaffneri (giganteum x myriochaetum)
x trachyodon (hyemale x variegatum)

*1 - not listed in the Hauke monographs