Overview

Comprehensive Description

Description

Perennial erect herbs. Leaves opposite below, alternate above. Flowers in terminal racemes. Calyx 5-lobed. Corolla strongly 2-lipped, variously coloured; tube gibbous at base; throat with a projecting palate, which closes the corolla mouth. Stamens 4. Capsule with 2 unequal cells
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Source: Flora of Zimbabwe

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Ecology

Associations

Foodplant / pathogen
gregarious, subepidermal, fuscous-honey coloured pycnidium of Diplodina coelomycetous anamorph of Diplodina passerinii infects and damages stem (esp. base) of Antirrhinum
Remarks: season: 5-9

In Great Britain and/or Ireland:
Foodplant / parasite
Mortierella chlamydospora parasitises live root of Antirrhinum

Foodplant / pathogen
abundant, sessile sporodochium of Myrothecium dematiaceous anamorph of Myrothecium roridum infects and damages dry, brittle stem (base) of Antirrhinum
Other: minor host/prey

Foodplant / sap sucker
Myzus persicae sucks sap of Antirrhinum

Foodplant / feeds on
Phytonemus pallidus feeds on live Antirrhinum

Foodplant / pathogen
Rhodococcus fascians infects and damages non-flowering plant of Antirrhinum
Other: major host/prey

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Evolution and Systematics

Functional Adaptations

Functional adaptation

Bumblebees get a foothold: snapdragons
 

The petals of flowers attract pollinators by providing non-slip surfaces via conical epidermal cells.

   
  "Approximately 80% of angiosperms produce petals with similar conical epidermal cells (Kay et al. 1981), and numerous suggestions as to their function have been made. These include the possibilities that they enhance petal colour, act as a direct tactile cue, increase the temperature of the flower, influence scent production or release, or influence the wettability of the flower surface (Kay et al. 1981; Kevan and Lane 1985)." (Dyer et al. 2007:46)


"The plant surface is by default flat, and development away from this default is thought to have some function of evolutionary advantage. Although the functions of many plant epidermal cells have been described, the function of conical epidermal cells, a defining feature of petals in the majority of insect-pollinated flowers, has not. The location and frequency of conical cells have led to speculation that they play a role in attracting animal pollinators. Snapdragon (Antirrhinum) mutants lacking conical cells have been shown to be discriminated against by foraging bumblebees. Here we investigated the extent to which a difference in petal surface structure influences pollinator behavior through touch-based discrimination...We show that foraging bumblebees are able to discriminate between different surfaces via tactile cues alone. We find that bumblebees use color cues to discriminate against flowers that lack conical cells—but only when flower surfaces are presented at steep angles, making them difficult to manipulate. This facilitation of physical handling is a likely explanation for the prevalence of conical epidermal petal cells in most flowering plants." (Whitney et al. 2009:948)
  Learn more about this functional adaptation.
  • Dyer, A.G.; Whitney, H.M.; Arnold, S.E.J.; Glover, B. J.; Chittka, L. 2007. Mutations perturbing petal cell shape and anthocyanin synthesis influence bumblebee perception of Antirrhinum majus flower colour. Arthropod-Plant Interactions. 1: 45-55.
  • Whitney, HM: Chittka, L; Bruce, TJA; Glover, BJ. 2009. Conical epidermal cells allow bees to grip flowers and increase foraging efficiency. Current Biology. 19(11): 948-953.
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Functional adaptation

Mutant gene flattens leaves: snapdragon
 

Mutant gene of snapdragons enhances photosynthesis by causing leaves to grow flat through uniform cell growth.

       
  Plants usually grow flat leaves to maximize the amount of sunlight they capture for photosynthesis. And now we know how. Unchecked, a leaf is more likely to be curved than flat. The leaf will buckle if cells near the edge grow more rapidly than cells near the center, and if the opposite happens the leaf becomes cup-shaped. Now it appears that the snapdragon uses a gene called CIN to ensure that cells in all regions of the leaf grow at a uniform rate, keeping the surface flat. (Courtesy of the Biomimicry Guild)
  Learn more about this functional adaptation.
  • Crawford, B. C. W.; Nath, U.; Carpenter, R.; Coen, E. S. 2004. Cincinnata controls both cell differentiation and growth in petal lobes and leaves of antirrhinum. Plant Physiology. 135(1): 244-253.
  • Nath, U; Crawford, BCW;Carpenter, R; Coen, E. 2003. Genetic control of surface curvature. Science. 299(5611): 1404-1407.
  • Coen, E. 2003. Way to grow. New Scientist. 8 November: 44-47.
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Wikipedia

Antirrhinum

This article is about the genus of plants commonly known as "Snapdragon". For other uses of "Snapdragon" or "Snap-dragon", see Snapdragon (disambiguation).

Antirrhinum is a genus of plants commonly known as dragon flowers or snapdragons, from the flowers' fancied resemblance to the face of a dragon that opens and closes its mouth when laterally squeezed. They are native to rocky areas of Europe, the United States, and North Africa.[1]

Description[edit]

The genus is morphologically diverse, particularly the New World group (Saerorhinum).[2] The genus is characterised by personate flowers with an inferior gibbous corolla.

Taxonomy[edit]

Antirrhinum used to be treated within the family Scrophulariaceae, but studies of DNA sequences have led to its inclusion in a vastly enlarged family Plantaginaceae within the tribe Antirrhineae.

Circumscription[edit]

The taxonomy of this genus is complex and not yet fully resolved at present. In particular the exact circumscription of the genus, especially the inclusion of the New World species (Saerorhinum) is contentious.[2] The situation is further complicated by the variety of terms in use for infrageneric ranks, especially of the Old World species, that is Antirrhinum, sensu stricto (eg Streptosepalum, Kicksiella, Meonantha).

The USDA Plants Database recognises only two species. A. majus (the garden snapdragon), the only species naturalised in North America, and Antirrhinum bellidifolium (the lilac snapdragon), now considered to be Anarrhinum bellidifolium (L.) Willd.[3] As of 2014 The Plant List accepts 21 species.[4]

A widely accepted scheme (Thompson 1988), placed 36 species in the genus in three sections. While many botanists accepted this broad circumscription (sensu lato), whose main departure from other classifications was the inclusion of the New World Saerorhinum,[5] others did not, restricting the genus to the Old World. (For a comparison of Thompson with earlier systems, see Oyama amd Baum, Table 1.) New species also continue to be discovered (see e.g. Romo et al., 1995).

In 2004 research into the molecular systematics of this group, and related species, by Oyama and Baum has confirmed that the genus sensu lato as described by Thompson is monophyletic, provided that one species (A. cyathiferum) is removed to the separate genus Pseudorontium, and the two species of Mohavea (Mohavea confertiflora and M. breviflora) are included. The species list given here follows these conclusions.[2]

This is the broad circumscription that includes the Old World Misopates and New World Sairocarpus. By contrast the narrow circumscription (sensu stricto) confines the genus to the monophyletic Old World perennial species with a diploid chromosome number of 16, distributed in the Mediterranean basin, approximately 25 species. (Tolety 2011), following the phylogenetic analysis of Vargas et al. (2004) suggesting they are a distimct group. Both Misopates and Sairocarpus are accepted names in The Plant List, and many of the New World species now have Sairocarpus as their accepted name, rather than Antirrhinum. It has been proposed that many of the New World Antirrhinum be now considered under Sairocarpus, in the forthcoming Flora of North America.[6]

Infrageneric subdivision[edit]

It is widely agreed that this broad group should be subdivided into three or four subgroups, but the level at which this should be done, and exactly which species should be grouped together, remain unclear. Some authors continue to follow Thompson in using a large genus Antirrhinum, which is then divided into several sections; others treat Thompson's genus as a tribe or subtribe, and divide it into several genera. For a comparison of earlier schemes see Mateu-Andrés and de Paco, Table 1 (2005)[7]

If the broad circumscription is accepted, its three sections as described by Thompson are as follows (two Old World, one New):

Snapdragons[edit]

While Antirrhinum majus is the plant that is usually meant by the term of "snapdragon" if used on its own, many other species in the genus, and in the family Scrophulariaceae more widely, have common names that include the word "snapdragon".

Species[edit]

Etymology[edit]

The word "antirrhinum" is derived from αντίρῥῑνόν "antirrhinon" which in turn was derived from Greek anti (αντί), "like," and rhis (ῥίς, ινοϛ), "nose", inus (-ινοϛ), "of" or "pertaining to"; thus, "like a nose", possibly referring to the nose-like capsule in its mature state.[9]

Distribution and habitat[edit]

For a map of the disribution of Old World species, see Figure 2 of Wilson and Hudson (2011).[10]

Ecology[edit]

Snapdragons are often considered as cold-season annual plants and do best in full or partial sun, in well drained soil (although they do require regular watering[11]). They are classified commercially as a range of heights: dwarf (6-8 inches), medium (15-30 inches) and tall (30-48 inches).

They are ecologically diverse, particularly the New World species (Saerorhinum).[2]

Cultivation[edit]

The Snapdragon is an important garden plant, widely cultivated from tropical to temperate zones as a bedding, rockery, herbaceous border or container plant. (Tolety 2011) Cultivars have showy white, crimson, or yellow bilabiate flowers (with two lips). It is also important as a model organism in botanical research, and its genome has been studied in detail.

Genetic studies[edit]

Antirrhinum is a genus that has been used from the earliest genetic studies of Gregor Mendel and Charles Darwin and was used as a model by Erwin Baur (Tolety 2011). Together with closely related genera, it has a become model organism for the investigation of the genetic basis of plant development, particularly floral development.[2][10] The genus is a typical example of incomplete dominance by the red allele with the anthocyanin pigment. Any cross between red-flowered and white-flowered snapdragons, give an intermediate and heterozygous phenotype with pink flowers, that carries both the dominant and recessive alleles.[12]

Several species of Antirrhinum are self-incompatible, meaning that a plant cannot be fertilised by its own pollen.[13] Self-incompatibility in the genus has been studied since the early 1900s.[13] Self-incompatibility in Antirrhinum species is controlled gametophytically and shares many important features with self-incompatibility systems in Rosaceae and Solanaceae.[14]

Uses[edit]

In addition to growing the plants for cut flowers, the seeds have been used to extract edible oils, particularly in Russia, while the leaves and flowers have been considered to possess antiphlogistic properties and have been used in poultices. A green dye has also been extracted from the flowers. (Tolety 2011)

Gallery[edit]

References[edit]

  1. ^ RHS A-Z encyclopedia of garden plants. United Kingdom: Dorling Kindersley. 2008. p. 1136. ISBN 1405332964. 
  2. ^ a b c d e Oyama, R. K.; Baum, D. A. (2004). "Phylogenetic relationships of North American Antirrhinum (Veronicaceae)". American Journal of Botany 91 (6): 918–925. doi:10.3732/ajb.91.6.918. PMID 21653448. 
  3. ^ USDA: Plants database
  4. ^ The Plant List: Antirrhinum
  5. ^ Thompson, D. M. (1988). Systematics of Antirrhinum (Scrophulariaceae) in the New World. Systematic Botany Monographs 22.
  6. ^ Barringer K. 2013. New combinations in Sairocarpus (Plantaginaceae). Phytoneuron 2013-34: 1–3.
  7. ^ I . Mateu-Andrés and Lorena de Paco. Allozymic Differentiation of the Antirrhinum majus and A. siculum Species Groups. Annals of Botany 95: 465–473, 2005. doi:10.1093/aob/mci055
  8. ^ M. Fernández-Mazuecos, J.L. Blanco-Pastor, and P. Vargas. A Phylogeny of Toadflaxes (Linaria Mill.) Based on Nuclear Internal Transcribed Spacer Sequences: Systematic and Evolutionary Consequences. International Journal of Plant Sciences. 174:pp. 234-249. 2013
  9. ^ "Antirrhinum orontium, Misopates orontium, Small Snapdragon, לוע-ארי קטן". Flowersinisrael.com. Retrieved 2011-07-15. 
  10. ^ a b Yvette Wilson and Andrew Hudson. The evolutionary history of Antirrhinum suggests that ancestral phenotype combinations survived repeated hybridizations. The Plant Journal (2011) 66, 1032–1043. doi:10.1111/j.1365-313X.2011.04563.x
  11. ^ Sunset Garden Plants
  12. ^ Hartl, Daniel L.; Elizabeth W. Jones (2005). Genetics : analysis of genes and genomes (sixth edition). Jones & Bartlett publishers. pp. 3.6 Incomplete Dominance and Epistasis. ISBN 0-7637-1511-5. 
  13. ^ a b Xue, Yongbiao; Rosemary Carpenter; Hugh G. Dickinson; Enrico S. Coen (May 1996). "Origin of allelic diversity in antirrhinum S locus RNases". The Plant Cell (American Society of Plant Physiologists) 8 (5): 805–814. doi:10.2307/3870283. JSTOR 3870283. PMC 161139. PMID 8672882. 
  14. ^ Takayama, Seiji; Akira Isogai (2005). "Self-incompatibility in plants". Annual Review of Plant Biology (Annual Reviews) 56: 467–489. doi:10.1146/annurev.arplant.56.032604.144249. PMID 15862104. 

Sources[edit]

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