Sphenophyllales is an extinct order

Order (biology)

In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 of articulate land plants and a sister group to the present-day Equisetales

Equisetales

The Equisetales is an order of pteridophytes with only one living genus Equisetum , of the family Equisetaceae. The fossil record includes additional extinct species in the Equisetaceae and the extinct families Calamitaceae and Archaeocalamitaceae....

 (horsetails). They are known known from fossils dating from the Devonian

Devonian

The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...

 to the Triassic

Triassic

The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

. They were common during the Late Pennsylvanian

Pennsylvanian

The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...

 to Early Permian

Permian

The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...

, with most of the fossils coming from the Carboniferous

Carboniferous

The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...

 period.

Description

Sphenophylls are small, slender branching plants, usually growing to a height of less than 1 m (3.3 ft) tall. The long stems range from 0.5 cm (0.196850393700787 in) to 1.2 cm (0.47244094488189 in) in diameter. The stems are jointed and ribbed with weak habits

Habit (biology)

Habit, when used in the context of biology, refers to the instinctive actions of animals and the natural tendencies of plants.In zoology, this term most often refers to specific behavioral characteristics, even when directly related to physiology...

, making it probable that these plants were vine-like

Vine

A vine in the narrowest sense is the grapevine , but more generally it can refer to any plant with a growth habit of trailing or scandent, that is to say climbing, stems or runners...

 when alive. The stem anatomy is protostelic (root

Root

In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...

-like), containing a solid primary xylem

Xylem

Xylem is one of the two types of transport tissue in vascular plants. . The word xylem is derived from the Classical Greek word ξυλον , meaning "wood"; the best-known xylem tissue is wood, though it is found throughout the plant...

 core with secondary xylem tissue present in some species. The leaves, which can be several centimeters long, are borne on each node in whorls (called verticels) and are wedge-shaped, fan-shaped, linear, or forked. Reproductive parts are either long terminal cones (consisting of two lobes, a sterile lower lobe and the fertile upper lobe bearing the sporangia) or loose strobili. All sphenophylls are homosporous, with monolete or trilete spore

Spore

In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...

s

Taxonomy

Sphenophyllales was first described by the British

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 botanist and geologist

Geologist

A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...

 Albert Charles Seward

Albert Charles Seward

Albert Charles Seward FRS was a British botanist and geologist.-Life:His first education was at Lancaster Grammar School and then on to St. John's College at Cambridge following his parents' wish to dedicate his life to the Church...

 in 1898. The name comes from the Greek words σφήν ("wedge") and φύλλον ("leaf").

Sphenophyllalean taxonomy is oftentimes derived from isolated fossil

Fossil

Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

ized parts of plants and classification may be based on the morphology

Plant morphology

Plant morphology or phytomorphology is the study of the physical form and external structure of plants. This is usually considered distinct from plant anatomy, which is the study of the internal structure of plants, especially at the microscopic level...

 and anatomy

Plant anatomy

Plant anatomy or phytotomy is the general term for the study of the internal structure of plants. While originally it included plant morphology, which is the description of the physical form and external structure of plants, since the mid-20th century the investigations of plant anatomy are...

 of sterile

Sterility (physiology)

Sterility is the physiological inability to effect sexual reproduction in a living thing, members of whose kind have been produced sexually. The term may be used in reference to* types of organism, such as the mule, a sterile hybrid;...

 plant parts (like leaves

Leaf

A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....

) or fructification

Fructification

Fructification is a term used in the plant morphology to denote the generative parts of the plant...

s (mainly the fossilized cones and the stratigraphically

Stratigraphy

Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....

-important spores found near them). This results in species that may actually by synonymous.
Sphenophyllales is typified by the genus Sphenophyllum

Sphenophyllum

Sphenophyllum is a genus in the order Sphenophyllales....

.

Phylogeny

The probable relationships within Equisetopsida

Equisetopsida

Equisetopsida, or Sphenopsida, is a class of plants with a fossil record going back to the Devonian. They are commonly known as horsetails...

 are shown in the cladogram below. The possible position of Ibyka has been added.