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Hornwort

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This page is about the nonvascular plant. For the aquatic plants known as hornwort: see Ceratophyllum
Hornwort
Hornwort land.jpg
Scientific Classification
  • Kingdom: Plantae
  • Division: Anthocerotophyta
  • Class: Anthocerotopsida
  • Order: Anthocerotales
Genera

Family Anthocerotaceae

Family Dendrocerotaceae

Family Notothyladaceae

Hornworts are non-vascular plant that have a close distinction to another bryophyte plant called a Liverwort. There are 100 known species of hornworts and liverworts. Hornworts are similar to mosses, which people are much more fond of as opposed to liverwort or hornworts.[1] In this order there are three different families and four different species, that categorize these plants.

Anatomy

The Thallus is one of the main distinctions between liverworts and mosses. Therefore the thallus' rhizoids are described as plain and simple, which discludes ventral scales. The rhizoids attach this plant to the ground. The sporophyte is seen as long and narrow, and has a central columella. The central columella is made up of sterile tissue as well as basal meristem. In some anthoceros, the hornwort presents pores in the capsule walls or lacks them. In dendroceros, the thallus is strap shaped, the midrib is strongly noticeable and quite defined. In megaceros, there are usually more than one chloroplast in just one epidermal cell. It grows to about 1-3 cm wide, as a dark-green hue. This plant is perennial, and tends to grow in clusters; this is considered a social-plantae. Archegonia are found and embedded in the surface of the dorsal, behind the apices. The compact ground tissue is measured as 5-8 layers deep. Close to the thallus, is the pores that arise, are similarly distinguished to the stomata. Behind this, the aperture sometimes becomes more round. Hornwort sporophytes tend to be about 3-7cm tall and range from 0.7-9cm. The pseudoelaters, is often unbranched or has somewhat branched filaments.[2]In the hornwort the thalloid holds one cell each with a single chloroplast. Therefore, the bottom and basal growth of the sporophyte is needle-like. The capsule and stomata are columnar.[3]

Reproduction

Sexually

Reproduction through alternation of generations in hornwort

Although hornworts can reproduce asexually by the fragmentation, sexual reproduction occurs through alternation of generations wherein the plant alternates between a gametophyte and sporophyte. The hornwort plant is similar to many other bryophyte plants in the way they reproduce. In a few types of species, the male and female, may either grow on just one single plant, however, the female and male organs may be separated onto two different plants. The archegonia which is the female organ, and antheridia which is the male organ, are encapsulated. They are located at the center region on the upper portion of the thallus. During the growth of the antheridia; the archegonia tends to break down from a result of water. Many multiple sperms become chemically attracted to the female eggs, these eggs are located at the bottom. The female eggs are chemically attracted to the the base of the archegonia. These then make their way through to become fertilized eggs through water. A fertilized egg is also called a [gamete]. And so, the zygotes are spread throughout the plant, they can then grow into the next generation. Sporophytes are horn-shaped and grow from the bottom of sheath under the surface of the gametophyte [thallus]. These hornworts [germinate] exactly from the spores.[4]

Gametophyte

During the reproduction of a Hornwort, there is a flat greensheet called, the gametophyte or thallus. The gametophyte in a hornwort is seen as wrinkled and green, as well as spiral-like. The color varies from dark green, light green, and even green-yellow. A hornwort[gametophyte] is usually portrayed as lobed or even sometimes wrinkled, this has a greenish colored sheet this is the thallus. The gametophyte, depending upon the type of genus, can grow spiral-like. The thallus' color is dark green, light green, even yellowish in Notothylas. The thallus can be many cells thick. In the genus Dendroceros the thallus is strap-like. Each tend to have a thick and central midrib with delicate lateral wings. The lateral wings are wavy and ruffle-like. Also, the thallus is connected to hook structures, the smooth rhizoids. Which bloom at the underside of the thallus.[5]

Sporophyte

Hornwort plants contrast in shape of the sporophyte generation. The hornworts generate spores inside of a greenish, horn-like stalk, instead. The color breaks down and is lucid, to the thallus of the plant.[6] With only one thallus many sporophytes can and may be produced. In a hornwort the sporophytes are erect and needle-like. The length of a hornwort sporophyte on average is 10 cm in length. In the genus Notothylas the sporophytes can be as small as 5 mm long, which are initially short and stout. They are banana-shaped. This structure is a spore capsule nonetheless. Most sporophytes apart from the genus Notothylas grows consistently clearly above the base. As the sporophytes grow, they are pushed outward. The sporophyte growth the youngest cells are near the base, and the oldest more upward to the top of more mature cells are the cells on the lower part of the sporophyte. Upon these mature cells The sporophyte relies upon the gametophyte greatly for carbohydrates; without the gametophyte or injury to the gametophyte the sporophyte could suffer. A sporophytes growth splits within its length; beginning at top working its way to the bottom. This happens so that the distribution of the sporophytes can amplify its period. The two halves remain together and joined at the top. The sporophyte even symmetrically splits along only one side of the structure to expand the slit on just one side of the capsule. An example of this is shown in the genus' Dendroceros and Megaceros sporophytes. In the genus Notothylas, the capsule doesn't split into two. The genus Notothylas, sporophytes can split this way; during this process, however they can decay.[7]

Ecology

hornwort distribution in the U S.

Typical Hornworts are found in many tropical areas, and mostly in these tropical areas the plant is diverse. To contrast, in places such as Europe, there are few of these species. They appear in Switzerland, hornworts tend to be annual in Northern Switzerland including other Central European areas as a result of climate changes.[8]

Gallery

References