''Hypnum'' is a genus of mosses belonging to the family

Hypnaceae Hypnaceae is a large family of moss with broad worldwide occurrence in the class Bryopsida, subclass Bryidae and order Hypnales. Genera include ''Hypnum'', ''Phyllodon'', and ''Taxiphyllum''. Ecology Some of the family species occur on the flo ...

. The genus has cosmopolitan distribution. A common name sometimes used for ''Hypnum'' moss is "carpet moss".

Distribution

''Hypnum'' species are found on all continents except for

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

. Species are typically found in temperate regions.

Habitat

''Hypnum'' species are typically found in moist forest areas on rotting logs, while some species are aquatic. Species can also be found living on soil, rocks, and live trees.

Identification

Identifying moss species in the field to the genus ''Hypnum'' by using a

hand lens A magnifying glass is a convex lens that is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle. A magnifying glass can be used to focus light, such as to concentrate the sun's radiation to crea ...

is considered quite feasible since most ''Hypnum'' species share common features with one another. A very useful defining characteristic of ''Hypnum'' mosses are their leaves which are often falcate- secund (meaning that they are sickle-shaped and point to one side of the plant). Another distinguishing characteristic of ''Hypnum'' mosses is the thick, green mats that they form, which earns them the common name "carpet moss". Distinguishing between different ''Hypnum'' species can be accomplished mainly by gametophytic features and sometimes by sporophytic features.

Description

Gametophyte characteristics

General form

Gametophytes range from small to large in size. Gametophytes are green, yellowish, or brown in colour, with the colouration appearing dull or glossy. Gametophytes can sometimes form tufts. Growth forms of ''Hypnum'' mosses vary from creeping to erect.

Stem and branching patterns

Stems have pseudoparaphyllia. Branching patterns include nearly unbranched, irregularly branched, or 1- or 2- times

pinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and in ...

Leaves

Branch leaves and stem leaves have similar shapes. Leaves are secund or falcate-secund, broadly to narrowly

ovate Ovate may refer to: * Ovate (egg-shaped) leaves, tepals, or other botanical parts *Ovate, a type of prehistoric stone hand axe *Ovates, one of three ranks of membership in the Welsh Gorsedd *Vates In modern English, the nouns vates () and ova ...

, and can be plicate. Leaf bases can sometimes be

decurrent ''Decurrent'' (sometimes decurring) is a term used in botany and mycology to describe plant or fungal parts that extend downward. In botany, the term is most often applied to leaf blades that partly wrap or have wings around the stem or petio ...

. Sometimes leaf margins are toothed on the distal region. Leaf margins can be recurved proximally and are usually flat (i.e., not recurved) at the distal edge. Leaf margins can sometimes be

sinuate A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...

at the proximal region. Leaf apices are either

acute Acute may refer to: Science and technology * Acute angle ** Acute triangle ** Acute, a leaf shape in the glossary of leaf morphology * Acute (medicine), a disease that it is of short duration and of recent onset. ** Acute toxicity, the adverse eff ...

acuminate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular ...

. Despite having similar shapes, branch leaves are smaller than stem leaves. Leaves have a double

costa Costa may refer to: Biology * Rib (Latin: ''costa''), in vertebrate anatomy * Costa (botany), the central strand of a plant leaf or thallus * Costa (coral), a stony rib, part of the skeleton of a coral * Costa (entomology), the leading edge of th ...

or an obscure costa that spans 1/4 of the leaf's length.

Laminal A laminal consonant is a phone (speech sound) produced by obstructing the air passage with the blade of the tongue, the flat top front surface just behind the tip of the tongue in contact with upper lip, teeth, alveolar ridge, to possibly, as ...

cells are exclusively smooth. Alar cells in the leaf bases are typically differentiated and range in shape from

hexagonal In geometry, a hexagon (from Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. Regular hexagon A '' regular hexagon'' has ...

triangular A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry. A triangle with vertices ''A'', ''B'', and ''C'' is denoted \triangle ABC. In Euclidean geometry, any three points, when non- collinea ...

, quadrate, or sub-quadrate. The outer perichaetial leaves are bent while the inner perichaetial leaves are erect. In terms of shape, perichaetial leaves can be ovate,

lanceolate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular ...

, or subulate. Apices of perichaetial leaves are acuminate.

Calyptra

Calyptra are exclusively naked and have no hair.

Sporophyte characteristics

Seta

Setae In biology, setae (singular seta ; from the Latin word for " bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. ...

are long and range in colour from yellowish to reddish.

Sporangium

Orientation of the sporangium can be erect, inclined, or horizontal. Sporangium shape varies from cylindrical to ovoid. The sporangium is also typically curved. There tends to be a contraction below the sporangium opening. All species have two rows of

peristome Peristome (from the Greek ''peri'', meaning 'around' or 'about', and ''stoma'', 'mouth') is an anatomical feature that surrounds an opening to an organ or structure. Some plants, fungi, and shelled gastropods have peristomes. In mosses In mosse ...

teeth. The outer surface of exostome teeth have zigzag lines as well as

lamellae Lamella (plural lamellae) means a small plate or flake in Latin, and in English may refer to: Biology * Lamella (mycology), a papery rib beneath a mushroom cap * Lamella (botany) * Lamella (surface anatomy), a plate-like structure in an animal * ...

. The annulus is either 1-3- times seriate or has very minimal amounts of cell differentiation. The operculum is conical to round in shape.

Spores In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...

produced by the sporangium are round and can be smooth or

papillose This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...

in texture.

Reproduction

In terms of

sexual reproduction Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote th ...

, ''Hypnum'' mosses are autoicous,

dioicous Dioicy () is a sexual system where archegonia and antheridia are produced on separate gametophytes. It is one of the two main sexual systems in bryophytes. Both dioicous () and monoicous gametophytes produce gametes in gametangia by mitosis ra ...

, or phyllodioicous. ''Hypnum'' mosses do not have any specialized forms of asexual reproduction.

Human use

Historically, ''Hypnum'' mosses were used to stuff bedding because they were falsely believed to have sleep-inducing properties. '' Hypnum curvifolium,'' commonly known as "sheet moss", is used by some florists.

Species

The number of species in the genus is unresolved. Depending on the source, the number of species ranges from around 50 to 220, or (according to

GBIF The Global Biodiversity Information Facility (GBIF) is an international organisation that focuses on making scientific data on biodiversity available via the Internet using web services. The data are provided by many institutions from around the ...

) up to 773. Some of the species in the genus are: * '' Hypnum acanthoneuron'' * '' Hypnum acanthophyllum'' * '' Hypnum circinale'' * '' Hypnum crispifolium'' * '' Hypnum cupressiforme'' * '' Hypnum curvifolium'' * '' Hypnum involuta''

Former species

* ''H. leptothallum'' , now a synonym of '' Eurohypnum leptothallum''

References

{{Taxonbar, from=Q141353 Hypnaceae Moss genera