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38-485: Gunnera is the sole genus of herbaceous flowering plants in the family Gunneraceae , which contains 63 species. Some species in this genus, namely those in the subgenus Panke , have extremely large leaves. Species in the genus are variously native to Latin America , Australia , New Zealand , Papuasia , Hawaii , insular Southeast Asia , Africa , and Madagascar . The stalks of some species are edible. Gunnera

76-510: A form of phylogenetic signal reserved for traits with broad-scale ecological ramifications (i.e. related to the Hutchinsonian niche ). Thus, phylogenetic niche conservatism is usually invoked with regards to closely related species occurring in similar environments. According to a recent review, the term niche conservatism traces its roots to a book on comparative methods in evolutionary biology. However, and as these authors also note,

114-458: A hybrid, Gunnera × cryptica . At least some species of Gunnera host endosymbiotic cyanobacteria such as Nostoc punctiforme . The cyanobacteria provide fixed nitrogen to the plant, while the plant provides fixed carbon to the microbe. The bacteria enter the plant via glands found at the base of each leaf stalk and initiate an intracellular symbiosis which is thought to provide the plant with fixed nitrogen in return for fixed carbon for

152-412: A pattern should be expected (i.e. follow from "Descent with modification" ) and, accordingly, only in instances where species resemble each other more than expected based on their phylogenetic relationships should one invoke the term phylogenetic niche conservatism. To take a single statistical test as an example, an unconstrained Brownian motion evolution process will result in a Blomberg's K value of 1;

190-597: A well-documented fossil history due to the presence of fossilized pollen spores, known by the palynotaxon Tricolpites reticulatus . It is a Gondwanan lineage, having originated in South America during the Cretaceous . The earliest fossilized pollen is known from the Late Cretaceous ( Turonian ) of Peru, about 90 million years ago, and within the following 10 million years, Gunnera had achieved

228-405: A woody stem, allowing plants to grow tall and transport water and nutrients over longer distances within the plant body. Since most woody plants are perennials with a longer life cycle because it takes more time and more resources (nutrients and water) to produce persistently living lignified woody stems, they are not as able to colonize open and dry ground as rapidly as herbs. The surface of herbs

266-527: A worldwide distribution, with fossil pollen grains being found in areas where it is not found today, such as western North America , mainland Australia , and Antarctica . Based on fossil pollen recovered from drilling cores, Gunnera is also known to have inhabited the now-submerged islands of the Ninetyeast Ridge during the Paleocene , likely having dispersed there from either Australasia or

304-546: A wound dressing. It also is eaten in various ways, largely the petioles, flower stalks and leaves, fresh and raw, preferably with skins and fibre removed, which is said to remove bitterness, but also cooked. The plant also is said to be used in making a beer. Herbaceous The fourth edition of the Shorter Oxford English Dictionary defines "herb" as: The same dictionary defines "herbaceous" as: Botanical sources differ from each other on

342-766: Is G. masafuerae of the Juan Fernandez Islands off the Chilean coast. They can have leaves up to 2.9 m (9 ft 6 in) in width on stout leaf stalks 1.5 m (4 ft 11 in) long and 11 cm ( 4 + 1 ⁄ 2  in) thick according to Skottsberg. These leafstalks or petioles are the thickest of any dicot, and probably also the most massive. On nearby Isla Más Afuera , G. peltata frequently has an upright trunk to 5.5 m (18 ft 1 in) in height by 25–30 cm (10–12 in) thick, bearing leaves up to 2 m (6 ft 7 in) wide. The Hoja de Pantano ( G. magnifica ) of

380-475: Is ephemeral and often seasonal in duration. By contrast, non-herbaceous vascular plants are woody plants that have stems above ground that remain alive, even during any dormant season, and grow shoots the next year from the above-ground parts – these include trees , shrubs , vines and woody bamboos . Banana plants are also regarded as herbaceous plants because the stem does not contain true woody tissue. Some herbaceous plants can grow rather large, such as

418-400: Is a catalyst for dew, which in arid climates and seasons is the main type of precipitation and is necessary for the survival of vegetation, i.e. in arid areas, herbaceous plants are a generator of precipitation and the basis of an ecosystem. Most of the water vapor that turns into dew comes from the air, not the soil or clouds. The taller the herb ( surface area is the main factor though),

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456-562: Is the only genus in the family Gunneraceae. The APG II system , of 2003, also recognizes this family and assigns it to the order Gunnerales in the clade core eudicots . The family then consisted of one or two genera, Gunnera and, optionally, Myrothamnus , the latter optionally segregated as a separate family, Myrothamnaceae . This represents a change from the APG system , of 1998, which firmly recognized two separate families, unplaced as to order. The APG III system and APG IV system recognizes

494-566: The Colombian Andes bears the largest leaf buds of any plant; up to 60 cm (2 ft) long and 40 cm (16 in) thick. The succulent leaf stalks are up to 2.7 m (8 ft 10 in) long. The massive inflorescence of small, reddish flowers is up to 2.3 m (7 ft 7 in) long and weighs about 13 kg. The flowers of Gunnera species are dimerous ( two sepals, two petals (or none) . two stamens (or one), and two carpels. Other giant Gunnera species within

532-512: The Cretaceous of North America have large leaves akin to those of Panke , and the most basal extant species within Panke ( G. mexicana ) is the most northern member. For this reason, it has been suggested that Panke originates from South American Gunnera that colonized North America during the Cretaceous and grew into giant forms, with the remaining South American Gunnera evolving into

570-819: The Serra do Mar mountains of southeastern Brazil , is perhaps the largest species, with reniform or sub-reniform leaves typically 1.5 to 2.0 meters (4 ft 11 in to 6 ft 7 in) long, not including the thick, succulent petiole which may be up to 2.5 meters (8 feet 2 inches) in length. The width of the leaf blade is typically 2.5 meters (8 feet 2 inches), but on two occasions cultivated specimens (in Dorset , England in 2011 and at Narrowwater, Ulster , Ireland in 1903) produced leaves fully 3.3 meters (10 feet 10 inches) in width. The seeds germinate best in very moist, but not wet, conditions and temperatures of 22–29 °C. Only slightly smaller

608-404: The analysis of annual growth rings in the secondary root xylem . Herbaceous plants do not produce perennializing above-ground structures using lignin , which is a complex phenolic polymer deposited in the secondary cell wall of all vascular plants. The development of lignin during vascular plant evolution provided mechanical strength, rigidity, and hydrophobicity to secondary cell walls creating

646-512: The bacterium. The Nostoc filled symbiotic tissue makes up just a small portion of the plant's total biomass. Gunnera is the only known genus of angiosperms that hosts cyanobacteria, and the only known landplants with intracellular cyanobionts . Although the endosymbionts enters the cell wall , they do not penetrate the cell membrane . This relationship may provide insights to allow the creation of novel symbioses between crop plants and cyanobacteria, allowing growth in areas lacking fixed nitrogen in

684-460: The beginning of the 20th century. In the meantime, in many publications it had been referred to as being in the Haloragaceae, variously misspelt (as for example "Halorrhagidaceae".) Such references still cause difficulties in consulting earlier works. However, currently Gunnera is firmly assigned to the monogeneric family Gunneraceae. Gunnera is thought to be a rather ancient group, with

722-544: The definition of "herb". For instance, the Hunt Institute for Botanical Documentation includes the condition "when persisting over more than one growing season, the parts of the shoot dying back seasonally". Some orchids, such as species of Phalaenopsis , are described in some sources (including the authoritative Plants of the World Online ) as "herbs" but with "leaves persistent or sometimes deciduous". In

760-785: The end of the growing season, but parts of the plant survive under or close to the ground from season to season (for biennials, until the next growing season, when they grow and flower again, then die). New growth can also develop from living tissues remaining on or under the ground, including roots , a caudex (a thickened portion of the stem at ground level) or various types of underground stems , such as bulbs , corms , stolons , rhizomes and tubers . Examples of herbaceous biennials include carrot , parsnip and common ragwort ; herbaceous perennials include potato , peony , hosta , mint , most ferns and most grasses . Phylogenetic niche conservatism The term phylogenetic niche conservatism has seen increasing use in recent years in

798-524: The family Gunneraceae and places Myrothamnus in Myrothamnaceae; both families are placed in the order Gunnerales in the core eudicots. The genus Gunnera was named after the Norwegian botanist Johann Ernst Gunnerus . At first it was assigned to the family Haloragaceae , though that presented difficulties that led to the general recognition of the family Gunneraceae, as had been proposed about

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836-609: The genus Musa , to which the banana belongs. Some relatively fast-growing herbaceous plants (especially annuals) are pioneers , or early-successional species. Others form the main vegetation of many stable habitats, occurring for example in the ground layer of forests , or in naturally open habitats such as meadow , salt marsh or desert . Some habitats, like grasslands and prairies and savannas , are dominated by herbaceous plants along with aquatic environments like ponds , streams and lakes . The age of some herbaceous perennial plants can be determined by herbchronology ,

874-750: The glossary of Flora of the Sydney Region , Roger Charles Carolin defines "herb" as a "plant that does not produce a woody stem", and the adjective "herbaceous" as meaning "herb-like, referring to parts of the plant that are green and soft in texture". Herbaceous plants include graminoids , forbs , and ferns . Forbs are generally defined as herbaceous broad-leafed plants, while graminoids are plants with grass-like appearance including true grasses , sedges, and rushes. Herbaceous plants most often are low-growing plants, different from woody plants like trees and shrubs , tending to have soft green stems that lack lignification and their above-ground growth

912-630: The idea is much older. For instance, Darwin observed in the Origin of Species that species in the same genus tend to resemble one another. This was not a matter of chance, as the entire Linnean taxonomy system is based on classifying species into hierarchically nested groups, e.g. a genus is (and was particularly at the time of Darwin's writing) by definition a collection of similar species. In modern times this pattern has come to be referred to as phylogenetic signal , "the tendency of related species to resemble each other more than species drawn at random from

950-403: The large-leaved Cretaceous Gunnera from North America may represent a distinct lineage that convergently evolved giant leaves similar to those of Panke , but did not leave any descendants. As of April 2023, Plants of the World Online accepts the following species separated by subgenus: In 2022, it was shown that plants in cultivation under the name Gunnera manicata were actually

988-452: The latter interpretation is employed, then phylogenetic niche conservatism can be seen as an extreme case of phylogenetic signal, and implies that the processes which prevent divergence are in operation in the lineage under consideration. Despite efforts by Jonathan Losos to end this habit, however, the former interpretation appears to frequently motivate scientific research. In this case, phylogenetic niche conservatism might best be considered

1026-553: The modern distribution of Gunnera is a consequence of long-distance dispersal from South America to other parts of the world, rather than relics of a former cosmopolitan distribution. The only species that diverged prior to the Cenozoic is Gunnera herteri of southeastern Brazil , which is thought to be the most ancient species of the genus, its lineage having diverged during the Late Cretaceous, roughly concurrent with

1064-517: The more dew it produces, so a short cut of the herbs necessitates watering. For example, if you frequently and shortly cut the grass without watering in an arid zone, then desertification occurs. Most herbaceous plants have a perennial (85%) life cycle but some are annual (15%) or biennial (<1%). Annual plants die completely at the end of the growing season or when they have flowered and fruited, and then new plants grow from seed. Herbaceous perennial and biennial plants may have stems that die at

1102-543: The oldest Gunnera fossil pollen from Peru. The persistence of the Gunnera crown group since the Cretaceous makes it unique among flowering plants, and may have been facilitated by strong niche conservatism , dispersal ability, and being able to aggressively colonize disturbed land. The 40–50 species vary enormously in leaf size, with the iconic large-leaved species belonging to the subgenus Panke . The giant rhubarb, or Campos des Loges ( Gunnera manicata ), native to

1140-439: The same tree ". Methods such as Abouheif’s C, Pagel's lambda, Blomberg's K, and Moran's I have been employed to test the statistical significance of the pattern. With regards to the term phylogenetic niche conservatism, many authors have taken a significant result here—i.e. that phylogenetic information can help "predict" species traits—to be evidence of phylogenetic niche conservatism. Other authors, however, advocate that such

1178-564: The scientific literature, though the exact definition has been a matter of some contention. Fundamentally, phylogenetic niche conservatism refers to the tendency of species to retain their ancestral traits. When defined as such, phylogenetic niche conservatism is therefore nearly synonymous with phylogenetic signal . The point of contention is whether or not "conservatism" refers simply to the tendency of species to resemble their ancestors, or implies that "closely related species are more similar than expected based on phylogenetic relationships". If

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1216-479: The soil. The stalks of G. tinctoria ( nalca ), from southern Chile and Argentina , are edible. Their principal use is fresh consumption, after peeling, but also they are prepared in salads, liquor or marmalade. Leaves of this species are used in covering curanto (a traditional Chilean food). Gunnera perpensa is a source of traditional medicine in southern Africa, both in veterinary and human ailments, largely in obstetric and digestive complaints, but also as

1254-481: The strict school of thought would only accept a K > 1 as evidence of phylogenetic niche conservatism. In an influential paper, Wiens and Donoghue laid out how phylogenetic niche conservatism might help explain the latitudinal diversity gradient . While support for the hypothesis that niche conservatism drives latitudinally structured variation in species richness has been found in some clades, overall, phylogenetic niche conservatism has not received strong support as

1292-545: The subgenus Misandra , with a low-lying, matlike growth. During the Cenozoic, the North American Panke would have colonized Hawaii and retreated southwards on the mainland before recolonizing South America. However, more recent phylogenetic evidence suggests that Misandra and Panke diverged only 15 million years ago, much too recent to assign the Cretaceous Gunnera to Panke . Due to this,

1330-587: The subgenus Panke are found throughout the Neotropics and Hawaii . Gunnera insignis is also known by the name "poor man's umbrella" in Costa Rica . Outside of the subgenus Panke , most of the more basal Gunnera species have small-to-medium-sized leaves. There are some species with moderately large leaves in Africa ( G. perpensa , in the subgenus Perpensum ) and Southeast Asia ( G. macrophylla , in

1368-605: The subgenus Pseudogunnera ), but the majority of more basal species are low-lying, mat-forming plants with small leaves. There are several small species are found in New Zealand , notably G. albocarpa , with leaves only 1–2 cm long, and also in South America, with G. magellanica having leaves 5–9 cm wide on stalks 8–15 cm long. The most basal species in the genus, G. herteri of Brazil, also has small leaves. Some fossil leaf impressions of Gunnera from

1406-475: The then-emergent Kerguelen Plateau islands. Due to the widespread distribution of Gunnera during the Cretaceous, it was previously thought that the modern disjunct distribution of the genus was a relic of this period. However, phylogenetic analysis indicates that the majority of Gunnera species, even those found on entirely different continents, diverged from each other during the Cenozoic , indicating that

1444-513: The underlying cause responsible for variation in how many species occur in a given habitat. It has, however, found considerable support as a factor driving which species occur in a given habitat. That is, the study of phylogenetic niche conservatism by itself has not put an end to long-standing debate over what drives the latitudinal diversity gradient across clades, but within specific clades and across specific environmental gradients (as opposed to latitude sensu stricto), it has found support as

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