A woodland ( / ˈ w ʊ d l ə n d / ) is, in the broad sense, land covered with woody plants ( trees and shrubs ), or in a narrow sense, synonymous with wood (or in the U.S., the plurale tantum woods ), a low-density forest forming open habitats with plenty of sunlight and limited shade (see differences between British , American and Australian English explained below). Some savannas may also be woodlands, such as savanna woodland , where trees and shrubs form a light canopy .
37-510: Woodlands may support an understory of shrubs and herbaceous plants including grasses . Woodland may form a transition to shrubland under drier conditions or during early stages of primary or secondary succession . Higher-density areas of trees with a largely closed canopy that provides extensive and nearly continuous shade are often referred to as forests . Extensive efforts by conservationist groups have been made to preserve woodlands from urbanization and agriculture . For example,
74-734: A class Equisetopsida ( Embryophyta ) encompassing all land plants. This is referred to as Equisetopsida sensu lato to distinguish it from the narrower use to refer to horsetails alone, Equisetopsida sensu stricto . They placed the lycopods into subclass Lycopodiidae and the ferns, keeping the term monilophytes, into five subclasses, Equisetidae, Ophioglossidae, Psilotidae, Marattiidae and Polypodiidae, by dividing Smith's Psilotopsida into its two orders and elevating them to subclass (Ophioglossidae and Psilotidae). Christenhusz et al. (2011) followed this use of subclasses but recombined Smith's Psilotopsida as Ophioglossidae, giving four subclasses of ferns again. Christenhusz and Chase (2014) developed
111-634: A few species (e.g., Cyathea brownii on Norfolk Island and Cyathea medullaris in New Zealand ). Roots are underground non-photosynthetic structures that take up water and nutrients from soil . They are always fibrous and are structurally very similar to the roots of seed plants. As in all vascular plants , the sporophyte is the dominant phase or generation in the life cycle . The gametophytes of ferns, however, are very different from those of seed plants. They are free-living and resemble liverworts , whereas those of seed plants develop within
148-487: A new classification of ferns and lycopods. They used the term Polypodiophyta for the ferns, subdivided like Smith et al. into four groups (shown with equivalents in the Smith system), with 21 families, approximately 212 genera and 10,535 species; This was a considerable reduction in the number of families from the 37 in the system of Smith et al., since the approach was more that of lumping rather than splitting. For instance
185-462: A protective coating called an indusium . The arrangement of the sporangia is important in classification. In monomorphic ferns, the fertile and sterile leaves look morphologically the same, and both are able to photosynthesize. In hemidimorphic ferns, just a portion of the fertile leaf is different from the sterile leaves. In dimorphic (holomorphic) ferns, the two types of leaves are morphologically distinct . The fertile leaves are much narrower than
222-430: A short-lived structure anchored to the ground by rhizoids called gametophyte which produce gametes. When a mature fertile frond bears sori, and spores are released, the spores will settle on the soil and send out rhizoids , while it develops into a prothallus . The prothallus bears spherical antheridia ( s.g. antheridium ) which produce antherozoids (male gametophytes) and archegonia ( s.g. archegonium ) which release
259-812: A significant input to the nitrogen nutrition of rice paddies . They also play certain roles in folklore. Extant ferns are herbaceous perennials and most lack woody growth. When woody growth is present, it is found in the stem. Their foliage may be deciduous or evergreen , and some are semi-evergreen depending on the climate. Like the sporophytes of seed plants, those of ferns consist of stems, leaves and roots. Ferns differ from spermatophytes in that they reproduce by spores rather than having flowers and producing seeds. However, they also differ from spore-producing bryophytes in that, like seed plants, they are polysporangiophytes , their sporophytes branching and producing many sporangia. Also unlike bryophytes, fern sporophytes are free-living and only briefly dependent on
296-568: A single oosphere . The antherozoid swims up the archegonium and fertilize the oosphere, resulting in a zygote, which will grow into a separate sporophyte, while the gametophyte shortly persists as a free-living plant. Carl Linnaeus (1753) originally recognized 15 genera of ferns and fern allies, classifying them in class Cryptogamia in two groups, Filices (e.g. Polypodium ) and Musci (mosses). By 1806 this had increased to 38 genera, and has progressively increased since ( see Schuettpelz et al (2018) ). Ferns were traditionally classified in
333-557: A sparse (10–30%) cover of trees, and an open woodland has a very sparse (<10%) cover. Woodlands are also subdivided into tall woodlands or low woodlands if their trees are over 30 m (98 ft) or under 10 m (33 ft) high, respectively. This contrasts with forests, which have more than 30% of their area covered by trees. Understory In forestry and ecology , understory ( American English ), or understorey ( Commonwealth English ), also known as underbrush or undergrowth , includes plant life growing beneath
370-500: Is polyphyletic , the term fern allies should be abandoned, except in a historical context. More recent genetic studies demonstrated that the Lycopodiophyta are more distantly related to other vascular plants , having radiated evolutionarily at the base of the vascular plant clade , while both the whisk ferns and horsetails are as closely related to leptosporangiate ferns as the ophioglossoid ferns and Marattiaceae . In fact,
407-578: Is intermediate between the eusporangiate ferns and the leptosporangiate ferns. Rai and Graham (2010) broadly supported the primary groups, but queried their relationships, concluding that "at present perhaps the best that can be said about all relationships among the major lineages of monilophytes in current studies is that we do not understand them very well". Grewe et al. (2013) confirmed the inclusion of horsetails within ferns sensu lato , but also suggested that uncertainties remained in their precise placement. Other classifications have raised Ophioglossales to
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#1732764700942444-524: Is the dominant phase. Ferns have complex leaves called megaphylls that are more complex than the microphylls of clubmosses . Most ferns are leptosporangiate ferns . They produce coiled fiddleheads that uncoil and expand into fronds . The group includes about 10,560 known extant species. Ferns are defined here in the broad sense, being all of the Polypodiopsida , comprising both the leptosporangiate ( Polypodiidae ) and eusporangiate ferns ,
481-634: Is used in British nature conservation to refer to any wooded land that has existed since 1600, and often (though not always) for thousands of years, since the last Ice Age (equivalent to the American term old-growth forest ) Woodlot is a closely related term in American forest management , which refers to a stand of trees generally used for firewood. While woodlots often technically have closed canopies, they are so small that light penetration from
518-479: The class Filices, and later in a Division of the Plant Kingdom named Pteridophyta or Filicophyta. Pteridophyta is no longer recognised as a valid taxon because it is paraphyletic . The ferns are also referred to as Polypodiophyta or, when treated as a subdivision of Tracheophyta (vascular plants), Polypodiopsida, although this name sometimes only refers to leptosporangiate ferns. Traditionally, all of
555-524: The forest canopy without penetrating it to any great extent, but above the forest floor . Only a small percentage of light penetrates the canopy so understory vegetation is generally shade-tolerant . The understory typically consists of trees stunted through lack of light, other small trees with low light requirements, saplings, shrubs, vines and undergrowth. Small trees such as holly and dogwood are understory specialists. In temperate deciduous forests , many understory plants start into growth earlier in
592-400: The pygmy marmoset . Fern The ferns ( Polypodiopsida or Polypodiophyta ) are a group of vascular plants (plants with xylem and phloem ) that reproduce via spores and have neither seeds nor flowers . They differ from mosses by being vascular, i.e., having specialized tissues that conduct water and nutrients, and in having life cycles in which the branched sporophyte
629-405: The canopy, and the shaded ground does not vary in temperature as much as open ground. This causes a proliferation of ferns , mosses , and fungi and encourages nutrient recycling , which provides favorable habitats for many animals and plants. The understory is the underlying layer of vegetation in a forest or wooded area, especially the trees and shrubs growing between the forest canopy and
666-538: The course of the year. As a rule forest understories also experience higher humidity than exposed areas. The forest canopy reduces solar radiation, so the ground does not heat up or cool down as rapidly as open ground. Consequently, the understory dries out more slowly than more exposed areas do. The greater humidity encourages epiphytes such as ferns and mosses, and allows fungi and other decomposers to flourish. This drives nutrient cycling , and provides favorable microclimates for many animals and plants , such as
703-417: The edge makes them ecologically closer to woodland than forest. North American forests vary widely in their ecology and are greatly dependent on abiotic factors such as climate and elevation. Much of the old-growth deciduous and pine-dominated forests of the eastern United States was harvested for lumber, paper pulp, telephone poles, creosote, pitch, and tar. In Australia, a woodland is defined as an area with
740-425: The end of the leafless season, understory plants take advantage of the shelter of the still leafless canopy plants to "leaf out" before the canopy trees do. This is important because it provides the understory plants with a window in which to photosynthesize without the canopy shading them. This brief period (usually 1–2 weeks) is often a crucial period in which the plant can maintain a net positive carbon balance over
777-399: The forest floor. Plants in the understory comprise an assortment of seedlings and saplings of canopy trees together with specialist understory shrubs and herbs. Young canopy trees often persist in the understory for decades as suppressed juveniles until an opening in the forest overstory permits their growth into the canopy. In contrast understory shrubs complete their life cycles in
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#1732764700942814-431: The fronds are branched more than once, it can also be a combination of the pinnatifid are pinnate shapes. If the leaf blades are divided twice, the plant has bipinnate fronds, and tripinnate fronds if they branch three times, and all the way to tetra- and pentapinnate fronds. In tree ferns, the main stalk that connects the leaf to the stem (known as the stipe), often has multiple leaflets. The leafy structures that grow from
851-494: The inclusion of Equisetaceae in the ferns, notably relating to the construction of their sperm and peculiarities of their roots. The leptosporangiate ferns are sometimes called "true ferns". This group includes most plants familiarly known as ferns. Modern research supports older ideas based on morphology that the Osmundaceae diverged early in the evolutionary history of the leptosporangiate ferns; in certain ways this family
888-478: The latter group including horsetails , whisk ferns , marattioid ferns , and ophioglossoid ferns . The fern crown group , consisting of the leptosporangiates and eusporangiates, is estimated to have originated in the late Silurian period 423.2 million years ago, but Polypodiales , the group that makes up 80% of living fern diversity, did not appear and diversify until the Cretaceous , contemporaneous with
925-474: The leptosporangiate ferns. The Marattiaceae are a primitive group of tropical ferns with large, fleshy rhizomes and are now thought to be a sibling taxon to the leptosporangiate ferns. Several other groups of species were considered fern allies: the clubmosses , spikemosses , and quillworts in Lycopodiophyta ; the whisk ferns of Psilotaceae ; and the horsetails of Equisetaceae . Since this grouping
962-555: The maternal gametophyte . The green , photosynthetic part of the plant is technically a megaphyll and in ferns, it is often called a frond . New leaves typically expand by the unrolling of a tight spiral called a crozier or fiddlehead into fronds . This uncurling of the leaf is termed circinate vernation . Leaves are divided into two types: sporophylls and tropophylls. Sporophylls produce spores; tropophylls do not. Fern spores are borne in sporangia which are usually clustered to form sori . The sporangia may be covered with
999-430: The rank of a fifth class, separating the whisk ferns and ophioglossoid ferns. The ferns are related to other groups as shown in the following cladogram: Lycophytes [REDACTED] Ferns [REDACTED] Gymnosperms [REDACTED] Angiosperms [REDACTED] The classification of Smith et al. in 2006 treated ferns as four classes: In addition they defined 11 orders and 37 families. That system
1036-549: The rise of flowering plants that came to dominate the world's flora. Ferns are not of major economic importance, but some are used for food, medicine, as biofertilizer , as ornamental plants, and for remediating contaminated soil. They have been the subject of research for their ability to remove some chemical pollutants from the atmosphere. Some fern species, such as bracken ( Pteridium aquilinum ) and water fern ( Azolla filiculoides ), are significant weeds worldwide. Some fern genera, such as Azolla , can fix nitrogen and make
1073-724: The shade of the forest canopy. Some smaller tree species, such as dogwood and holly , rarely grow tall and generally are understory trees. The canopy of a tropical forest is typically about 10 m (33 ft) thick, and intercepts around 95% of the sunlight. The understory therefore receives less intense light than plants in the canopy and such light as does penetrate is impoverished in wavelengths of light that are most effective for photosynthesis. Understory plants therefore must be shade tolerant —they must be able to photosynthesize adequately using such light as does reach their leaves. They often are able to use wavelengths that canopy plants cannot. In temperate deciduous forests towards
1110-476: The spore producing vascular plants were informally denominated the pteridophytes , rendering the term synonymous with ferns and fern allies . This can be confusing because members of the division Pteridophyta were also denominated pteridophytes ( sensu stricto ). Traditionally, three discrete groups have been denominated ferns: two groups of eusporangiate ferns, the families Ophioglossaceae ( adder's tongues , moonworts , and grape ferns) and Marattiaceae ; and
1147-417: The spore wall and are dependent on the parent sporophyte for their nutrition. A fern gametophyte typically consists of: The lifecycle of a fern involves two stages, as in club mosses and horsetails . In stage one, the spores are produced by sporophytes in sporangia , which are clustered together in sori ( s.g. sorus ), developing on the underside of fertile fronds. In stage two, the spores germinate into
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1184-496: The sterile leaves, and may have no green tissue at all, as in the Blechnaceae and Lomariopsidaceae . The anatomy of fern leaves can be anywhere from simple to highly divided, or even indeterminate (e.g. Gleicheniaceae , Lygodiaceae ). The divided forms are pinnate , where the leaf segments are completely separated from one other, or pinnatifid (partially pinnate), where the leaf segments are still partially connected. When
1221-463: The stipe are known as pinnae and are often again divided into smaller pinnules. Fern stems are often loosely called rhizomes , even though they grow underground only in some of the species. Epiphytic species and many of the terrestrial ones have above-ground creeping stolons (e.g., Polypodiaceae ), and many groups have above-ground erect semi-woody trunks (e.g., Cyatheaceae , the scaly tree ferns). These can reach up to 20 meters (66 ft) tall in
1258-477: The whisk ferns and ophioglossoid ferns are demonstrably a clade , and the horsetails and Marattiaceae are arguably another clade. Smith et al. (2006) carried out the first higher-level pteridophyte classification published in the molecular phylogenetic era, and considered the ferns as monilophytes, as follows: Molecular data, which remain poorly constrained for many parts of the plants' phylogeny, have been supplemented by morphological observations supporting
1295-642: The woodlands of Northwest Indiana have been preserved as part of the Indiana Dunes . Woodland is used in British woodland management to mean tree-covered areas which arose naturally and which are then managed. At the same time, forest is usually used in the British Isles to describe plantations , usually more extensive, or hunting Forests , which are a land use with a legal definition and may not be wooded at all. The term ancient woodland
1332-472: The year than the canopy trees, to make use of the greater availability of light at that particular time of year. A gap in the canopy caused by the death of a tree stimulates the potential emergent trees into competitive growth as they grow upwards to fill the gap. These trees tend to have straight trunks and few lower branches. At the same time, the bushes, undergrowth, and plant life on the forest floor become denser. The understory experiences greater humidity than
1369-844: Was a consensus of a number of studies, and was further refined. The phylogenetic relationships are shown in the following cladogram (to the level of orders). This division into four major clades was then confirmed using morphology alone. Lycopodiophytes (club mosses, spike mosses, quillworts) Spermatophytes (seed plants) Equisetales (horsetails) [REDACTED] Ophioglossales (grapeferns etc.) Psilotales (whisk ferns) [REDACTED] Marattiales [REDACTED] Osmundales [REDACTED] Hymenophyllales (filmy ferns) [REDACTED] Gleicheniales [REDACTED] Schizaeales Salviniales (heterosporous) Cyatheales (tree ferns) [REDACTED] Polypodiales [REDACTED] Subsequently, Chase and Reveal considered both lycopods and ferns as subclasses of
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