Equisetum is a genus of vascular plants that includes horsetails. The plant body has an underground rhizome and aerial stems. Stems are typically 15-60 cm tall with ridges and grooves. They grow in wet habitats like stream banks. The stem has a silica-coated epidermis and stomata located in grooves. Beneath the epidermis is a cortex with sclerenchyma below ridges and air canals below grooves. Vascular bundles alternate with air canals. Roots have a multi-layered cortex and a protostelic stele. Stems grow through the activity of intercalary meristems between nodes.

1. Equisetum
DR. RASIKA N. PATIL
ASSISTANT PROFESSOR
DEPARTMENT OF BOTANY
SHRI SHIVAJI COLLEGE OF ARTS COMMERCE AND SCIENCE AKOLA

2. Kingdom: Plantae
Division: Polypodiophyta
Class: Polypodiopsida
Subclass: Equisetidae
Order: Equisetales
Family: Equisetaceae
Genus: Equisetum sp.
Habit of Equisetum

3. • Habit and Habitat of Equisetum:
1) The plant body of Equisetum has an aerial part and an underground rhizome part. The rhizome is
perennial, horizontal, branched and creeping in nature. The aerial part is herbaceous and usually annual.
Majority of the species are small with a size range in between 15 and 60 cm in height and 2.0 cm in
diameter.
2) However some species grow up in higher heights, though their stem are relatively thin showing vine-
like habit and climb over adjacent forest trees.
3) Equisetums generally grow in wet or damp habitats and are particularly common along the banks of
streams or irrigation canals. However, some species are adapted to xeric condition.
4) Some species of Equisetum are indicators of the mineral content of the soil in which they grow. Some
species accumulate gold (about 4.5 ounce per ton of dry wt.), thus they are considered as ‘gold indicator
plants.
5) Hence these plants help in prospection/exploration for new ore deposits. In Equisetum, silica is
deposited on the outer wall of the epidermal cells giving the characteristic rough feeling, thus it
provides a protective covering against predators and pathogens.

5. It is wavy in outline because of the presence of ridges and grooves.
Outermost layer is the epidermis, cells of which have a deposit of silica in their outer and lateral walls.
Due to the presence of silica, the stem appears hard and rough to touch.
The continuity of epidermis is broken by sunken stomata present in each groove. In each sunken stoma, the
guard cells are covered completely by subsidiary cells, thus giving the appearance of two sets of guard
cells.
Below the epidermis is present a-well-developed cortex.
Just below each ridge is present a large patch of sclerenchyma, which is mechanical in function.
Sclerenchyma is also present below the grooves in between chlorenchyma.
Inner to be sclerenchyma is present chloren-chymatous tissue below each ridge. It is photosynthetic in
function. It extends up to the epidermis in each groove, where lie the stomata.Rest of the cortex is
parenchymatous and many layered.
Just below each groove is present a large air canal in the parenchymatous cortex. It is known as vallecular
canal.
Innermost layer of cortex is the endodermis, the cells of which contains casparian strips. But in species like
E. sylvaticum, a layer of inner endodermis is also present . In E. litorale, each vascular bundle contains its
individual endodermis.Below the endodermis is present a single-layered pericycle.
Vascular bundles are present below the ridges, i.e., alternate to the vallecular canals of the cortex. They are
present in the ring.The number of vascular bundles and vallecular canals is equal to the number of ridges
and grooves, respectively

7. T.S Root of Equisetum
Outermost layer is epidermis, from which arise many root hairs.
Cortex is thick and multi-layered.
Outer zone of cortex consists of 3 to 4-celled thick exodermis.
 Inner zone is parenchymatous with many intercellular spaces.
Endodermis is two-layered.
 Pericycle is absent.
 Stele is a protostele, which is triarch or tetrarch.
In the centre is present a large metaxylem tracheid having many
protoxylem groups towards the periphery?
 Phloem is present in between the angles of protoxylem

8. T. S. Of Stem

9. • In T.S., the stem of Equisetum appears wavy in outline with ridges and furrows. The epidermal
cell walls are thick, cuticularised and have a deposition of siliceous material.
• Stomata are distributed only in the furrows between the ridges. A hypodermal sclerenchymatous
zone is present below each ridge which may extend up to stele in E. giganteum.
• The cortex is differentiated into outer and inner regions.
• The outer cortex is chlorenchymatous, while the inner cortex is made up of thin-walled
parenchymatous cells. There is a large air cavity in the inner cortex corresponding to each furrow
and alternating with the ridges, known as vallecular canal.
• These are schizolysigenous canals extending the entire length of internodes and form a distinct
aerating system.
• New leaves and branches of Equisetum are produced by the apical meristem, however, most of
the length of the stem are due to the activity of intercalary meristem located just above each node.
• The activity of intercalary meristem causes rapid elongation of the inter- nodal region.