34-479: Huperzioideae is a subfamily of lycopsids in the family Lycopodiaceae . It has sometimes been recognized as a separate family, Huperziaceae . The Pteridophyte Phylogeny Group classification of 2016 (PPG I) recognizes three extant genera: The plants are distinct from those of other members of the Lycopodiaceae in having erect (not creeping) growth; and in their spore -bearing structures being produced in
68-431: A 'cf.' (from Latin confer , compare, before a taxon name); such a convention is especially widespread in palaeontology. In zoological nomenclature, " incertae sedis " is not a nomenclatural term at all per se , but is used by taxonomists in their classifications to mean "of uncertain taxonomic position". In botany, a name is not validly published if it is not accepted by the author in the same publication. In zoology,
102-447: A formal phylogenetic analysis is conducted that does not include a certain taxon, the authors might choose to label the taxon incertae sedis instead of guessing its placement. This is particularly common when molecular phylogenies are generated, since tissue for many rare organisms is hard to obtain. It is also a common scenario when fossil taxa are included, since many fossils are defined based on partial information. For example, if
136-595: A modified shoot system acting as roots, bipolar and secondary growth , and an upright stance. The remains of Lepidodendron lycopods formed many fossil coal deposits. In Fossil Grove , Victoria Park, Glasgow, Scotland, fossilized lycophytes can be found in sandstone . The Lycopodiopsida had their maximum diversity in the Pennsylvanian (Upper Carboniferous), particularly tree-like Lepidodendron and Sigillaria that dominated tropical wetlands. The complex ecology of these tropical rainforests collapsed during
170-527: A more broadly defined taxon of lycophytes that includes some extinct groups more distantly related to extant lycophytes, such as the zosterophylls . For example, Kenrick & Crane (1997) use the subdivision Lycophytina for this purpose, with all extant lycophytes falling within the class Lycopsida. Other sources exclude the zosterophylls from any "lycophyte" taxon. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I),
204-429: A name proposed conditionally may be available under certain conditions. For uncertainties at lower levels, some authors have proposed a system of "open nomenclature", suggesting that question marks be used to denote a questionable assignment. For example, if a new species was given the specific epithet album by Anton and attributed with uncertainty to Agenus , it could be denoted " Agenus ? album Anton (?Anton)";
238-402: A taxon, which may be expressed, among others, by using a question mark after or before a taxon name. This should be distinguished from the situation where either it is uncertain how to use a name, often because the types have been lost ( nomen dubium , species inquirenda ), or whether a poorly preserved specimen should be included within a given species or genus, which is often expressed using
272-606: Is an endophytic fungus present in Huperzia serrata that produces Huperzine A , a biomedical compound which has been approved as a drug in China and a dietary supplement in the U.S. to treat Alzheimer's Disease. This fungal endophyte can be cultivated much more easily and on a much larger scale than H. serrata itself which could increase the availability of Huperzine A as a medicine. The spores of lycopods are highly flammable and so have been used in fireworks . Lycopodium powder ,
306-472: Is completely absent in seed plants except for Ginkgo and cycads). Because only two flagella puts a size limit on the genome, we find the largest known genomes in the clade in Isoetes , as multiflagellated sperm is not exposed for the same selection pressure as biflagellate sperm in regard of size. The extant lycophytes are vascular plants (tracheophytes) with microphyllous leaves , distinguishing them from
340-658: Is developed enough for independence is the new plant dropped to the ground. Many club-moss gametophytes are mycoheterotrophic and long-lived, residing underground for several years before emerging from the ground and progressing to the sporophyte stage. Lycopodiaceae and spikemosses ( Selaginella ) are the only vascular plants with biflagellate sperm, an ancestral trait in land plants otherwise only seen in bryophytes . The only exceptions are Isoetes and Phylloglossum , which independently has evolved multiflagellated sperm cells with approximately 20 flagella (sperm flagella in other vascular plants can count at least thousand, but
374-771: The Induan (earliest Triassic), particularly Pleuromeia . After the worldwide Permian–Triassic extinction event , members of this group pioneered the repopulation of habitats as opportunistic plants. The heterogeneity of the terrestrial plant communities increased markedly during the Middle Triassic when plant groups like horsetails, ferns, pteridosperms , cycads , ginkgos and conifers resurfaced and diversified quickly. Lycophytes form associations with microbes such as fungi and bacteria, including arbuscular mycorrhizal and endophytic associations. Arbuscular mycorrhizal associations have been characterized in all stages of
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#1732798797315408-512: The Pteridophyte Phylogeny Group (PPG I), which places them all in the class Lycopodiopsida, which includes the classes Isoetopsida and Selaginellopsida used in other systems. (See Table 2 .) Alternative classification systems have used ranks from division (phylum) to subclass. In the PPG ;I system, the class is divided into three orders, Lycopodiales , Isoetales and Selaginellales . Club-mosses (Lycopodiales) are homosporous, but
442-537: The euphyllophytes (plants with megaphyllous leaves ). The sister group of the extant lycophytes and their closest extinct relatives are generally believed to be the zosterophylls , a paraphyletic or plesion group. Ignoring some smaller extinct taxa, the evolutionary relationships are as shown below. (multiple branches, incertae sedis ) living lycophytes and their extinct close relatives ferns & horsetails spermatophytes (seed plants) As of 2019 , there
476-559: The genus may be assigned incertae sedis . This excerpt from a 2007 scientific paper about crustaceans of the Kuril–Kamchatka Trench and the Japan Trench describes typical circumstances through which this category is applied in discussing: ...the removal of many genera from new and existing families into a state of incertae sedis. Their reduced status was attributed largely to poor or inadequate descriptions but it
510-488: The "(?Anton)" indicates the author that assigned the question mark. So if Anton described Agenus album , and Bruno called the assignment into doubt, this could be denoted " Agenus ? album (Anton) (?Bruno)", with the parentheses around Anton because the original assignment (to Agenus ) was modified (to Agenus ?) by Bruno. This practice is not included in the International Code of Zoological Nomenclature , and
544-687: The Lycopodiopsida first appear in the Silurian period, along with a number of other vascular plants. The Silurian Baragwanathia longifolia is one of the earliest identifiable species. Lycopodolica is another Silurian genus which appears to be an early member of this group. The group evolved roots independently from the rest of the vascular plants. From the Devonian onwards, some species grew large and tree-like. Devonian fossil lycopsids from Svalbard , growing in equatorial regions, raise
578-679: The Middle Pennsylvanian due to a change in climate. In Euramerica , tree-like species apparently became extinct in the Late Pennsylvanian, as a result of a transition to a much drier climate, giving way to conifers , ferns and horsetails . In Cathaysia (now South China), tree-like species survived into the Permian . Nevertheless, lycopodiopsids are rare in the Lopingian (latest Permian), but regained dominance in
612-561: The axils of unmodified leaves , rather than in terminal club-like structures. The subfamily also has a basal chromosome count of n =67, versus counts of n =23, 34 in the Lycopodiaceae. Lycopodiopsida See Table 1 . Lycopodiopsida is a class of vascular plants also known as lycopods or lycophytes . Members of the class are also called clubmosses , firmosses , spikemosses and quillworts . They have dichotomously branching stems bearing simple leaves called microphylls and reproduce by means of spores borne in sporangia on
646-580: The dried spores of the common clubmoss, was used in Victorian theater to produce flame-effects. A blown cloud of spores burned rapidly and brightly, but with little heat. (It was considered safe by the standards of the time.) Incertae sedis Incertae sedis ( Latin for 'of uncertain placement') or problematica is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In
680-408: The extant lycophytes (and their closest extinct relatives) varies widely. Table 1 below shows some of the highest ranks that have been used. Systems may use taxa at a rank lower than the highest given in the table with the same circumscription; for example, a system that uses Lycopodiophyta as the highest ranked taxon may place all of its members in a single subclass. Some systems use a higher rank for
714-534: The extant lycophytes as shown below. Some extinct groups, such as zosterophylls , fall outside the limits of the taxon as defined by the classifications in Table 1 above. However, other extinct groups fall within some circumscriptions of this taxon. Taylor et al. (2009) and Mauseth (2014) include a number of extinct orders in their division (phylum) Lycophyta, although they differ on the placement of some genera. The orders included by Taylor et al. are: Mauseth uses
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#1732798797315748-411: The genera Selaginella (spikemosses) and Isoetes (quillworts) are heterosporous, with female spores larger than the male. As a result of fertilisation, the female gametophyte produces sporophytes. A few species of Selaginella such as S. apoda and S. rupestris are also viviparous ; the gametophyte develops on the mother plant, and only when the sporophyte's primary shoot and root
782-683: The lycophyte lifecycle: mycoheterotrophic gametophyte, photosynthetic surface-dwelling gametophyte, young sporophyte, and mature sporophyte. Arbuscular mycorrhizae have been found in Selaginella spp. roots and vesicles. During the mycoheterotrophic gametophyte lifecycle stage, lycophytes gain all of their carbon from subterranean glomalean fungi. In other plant taxa, glomalean networks transfer carbon from neighboring plants to mycoheterotrophic gametophytes. Something similar could be occurring in Huperzia hypogeae gametophytes which associate with
816-749: The order †Asteroxylales, placing Baragwanathia in the Protolepidodendrales. The relationship between some of these extinct groups and the extant ones was investigated by Kenrick and Crane in 1997. When the genera they used are assigned to orders, their suggested relationship is: †Drepanophycales († Asteroxylon , † Baragwanathia , † Drepanophycus ) Lycopodiales †Protolepidodendrales († Leclercqia , † Minarodendron ) Selaginellales ( Selaginella , including subg. Stachygynandrum and subg. Tetragonostachys ) Isoetales ( Isoetes ) †Lepidodendrales († Paralycopodites ) The Lycopodiopsida are distinguished from other vascular plants by
850-478: The phylogeny was constructed using soft tissue and vertebrae as principal characters and the taxon in question is only known from a single tooth, it would be necessary to label it incertae sedis . If conflicting results exist or if there is not a consensus among researchers as to how a taxon relates to other organisms, it may be listed as incertae sedis until the conflict is resolved. The term incertae sedis refers to uncertainty about phylogenetic position of
884-430: The plant grew, leaving only a small cluster of leaves at the top. The lycopsids had distinctive features such as Lepidodendron lycophytes, which were marked with diamond-shaped scars where they once had leaves. Quillworts (order Isoetales) and Selaginella are considered their closest extant relatives and share some unusual features with these fossil lycopods, including the development of both bark, cambium and wood ,
918-489: The possession of microphylls and by their sporangia, which are lateral as opposed to terminal and which open (dehisce) transversely rather than longitudinally. In some groups, the sporangia are borne on sporophylls that are clustered into strobili. Phylogenetic analysis shows the group branching off at the base of the evolution of vascular plants and they have a long evolutionary history. Fossils are abundant worldwide, especially in coal deposits . Fossils that can be ascribed to
952-517: The possibility that they drew down enough carbon dioxide to change the Earth's climate significantly. During the Carboniferous , tree-like plants (such as Lepidodendron , Sigillaria , and other extinct genera of the order Lepidodendrales ) formed huge forests that dominated the landscape. Unlike modern trees, leaves grew out of the entire surface of the trunk and branches, but fell off as
986-552: The same glomalean phenotypes as nearby Huperzia hypogeae sporophytes. Fungal endophytes have been found in many species of lycophyte, however the function of these endophytes in host plant biology is not known. Endophytes of other plant taxa perform roles such as improving plant competitive fitness, conferring biotic and abiotic stress tolerance, promoting plant growth through phytohormone production or production of limiting nutrients. However, some endophytic fungi in lycophytes do produce medically relevant compounds. Shiraia sp Slf14
1020-422: The sides of the stems at the bases of the leaves. Although living species are small, during the Carboniferous , extinct tree-like forms ( Lepidodendrales ) formed huge forests that dominated the landscape and contributed to coal deposits. The nomenclature and classification of plants with microphylls varies substantially among authors. A consensus classification for extant (living) species was produced in 2016 by
1054-611: The system of open nomenclature , uncertainty at specific taxonomic levels is indicated by incertae familiae (of uncertain family), incerti subordinis (of uncertain suborder), incerti ordinis (of uncertain order) and similar terms. When formally naming a taxon, uncertainty about its taxonomic classification can be problematic. The International Code of Nomenclature for algae, fungi, and plants , stipulates that "species and subdivisions of genera must be assigned to genera, and infraspecific taxa must be assigned to species, because their names are combinations", but ranks higher than
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1088-455: The three orders are placed in a single class, Lycopodiopsida, holding all extant lycophyte species. Older systems have used either three classes, one for each order, or two classes, recognizing the closer relationship between Isoetales and Selaginellales. In these cases, a higher ranked taxon is needed to contain the classes (see Table 1). As Table 2 shows, the names "Lycopodiopsida" and "Isoetopsida" are both ambiguous. The PPG I system divides up
1122-430: Was accepted that some of the vagueness in the analysis was due to insufficient character states. It is also evident that a proportion of the characters used in the analysis, or their given states for particular taxa, were inappropriate or invalid. Additional complexity, and factors that have misled earlier authorities, are intrusion by extensive homoplasies , apparent character state reversals and convergent evolution . If
1156-401: Was broad agreement, supported by both molecular and morphological evidence, that the extant lycophytes fell into three groups, treated as orders in PPG I, and that these, both together and individually, are monophyletic , being related as shown in the cladogram below: lycopodiales Isoetales Selaginellales The rank and name used for the taxon holding
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