Order Gunnerales / Rhubarb & Resurrection Flowers


    Order Gunnerales

    Gunnerales is an order of dicotyledonous flowers with members with ellagic acids, abundant plastids in their phloem cells, hydathodal teeth in the lamina margins of the leaf, and small flowers.

    The Gunnerales plants are dioeciousWhat is dioecious?Pertaining to plants, individuals of which bear either staminate or pistillate flowers, but not both. and generally pollinated via wind. Most Gunneraceae species are found in the tropical regions above the equator, while Myrothamnaceae are endemic to Madagascar and Africa. In addition, the giant rhubarb and the resurrection plants are found under the Gunnerales order.

    Gunnerales Families

    Gunnerales Families

    Gunnerales have 2 families, 2 genera, and 42-52 species[1]. The two families are so different in appearance that grouping them was a surprise. But despite the distinct dissimilarities of the size and the habitat of the two families, they manifest the same anatomy down to very small details under the electron microscope and DNA analysis.

    • Gunneraceae (Giant rhubarb)
    • Myrothamnaceae (Resurrection plants)

    Gunnerales Distribution

    Gunnerales Distribution

    The members of Gunneraceae (1 genus and 40-50 species) are usually huge herbs living in humid surroundings. Thirty-eight species of Gunnera[2] are in the Neotropics. The species of Gunnera are found in countries like Bolivia, Brazil, Central America, and Mexico. They are also present in Colombia, Ecuador, Peru, Argentina, Chile, and Venezuela.

    The 2 species of Myrothamnaceae (1 genus and 2 species each[3] ) are xerophytes (plants adapted to dry habitat). Myrothamnaceae members are distributed in Africa and Madagascar.

    Gunnerales Characteristics

    Gunnerales Characteristics

    • Plant type: Members are perennial herbs or dioecious shrubs. The two families under this order both have ellagic acid. The Gunnerales do not have the mitochondrial gene rps2 and benzylisoquinoline alkaloids.
    • Stem: Their phloem cells have abundant plastids. Most species have stout and pachycaulous stems.
    • Leaves: The lamina margins of the leaf contain hydathodal teeth. The secondary veins of the plants are palmate.
    • Flowers and Inflorescences: The plants are dioecious, and the flowers are small. The flowers are in panicles or catkin-like inflorescences.
    • Sepals and Petals: The flowers do not have much perianth. The Gunnerales members have 2 sepals and 2 petals. Other species lack petals while others completely lack the perianth.
    • Stamens and ovary: The stamens are generally 2, and the carpels are 2-3.
    • Ovary and Fruit: The Gunnerales plants have an inferior ovary. The fruit is a berry or a capsule.
    • Seeds: The seeds are endospermic.

    Gunnerales Flowers

    Gunnerales Flowers and Reproduction

    Gunnerales Flowers and Reproduction

    Members of Gunnerales have small flowers. Both Gunneraceae and Myrothamnaceae don’t have much perianth in their flowers, even though some kind of perianth may be present in this order as being in a pleisiomorphic state(ancestral character state).

    • The Gunnera plants have relatively large and brownish panicles bearing many tiny red-brown flowers. The small flowers of Gunneraceae have 2 sepals, 2 petals, 2 stamens, and 2 carpels (dimerous)[4]. The petal primordia in G. dentataemerges after the sepals, but they remain reduced.
    • The petals are absent in G. macrophylla. Two petal primordia in G. monoicastart to emerge at an early stage. Still, they terminate during the early development of the flower. The species G. herteri completely lacks perianth. Members of Gunneraceae have an inferior ovary. Species are pollinated via wind. The fruits of the members are small, red, and berry-like.
    • The male and female reproductive organs of Myrothamnaceae[5] are on separate individuals (dioecious). This family’s tiny flowers usually occur on short lateral branches in catkin-like inflorescences that bloom from September to November. There are 3-6 stamens with reddish anthers.
    • At maturity, the anthers produce an ample amount of tricolpate pollen grains. The female flowers are zygomorphicWhat is zygomorphic?A characteristic of the flower having only one plane of symmetry, as in a pea or snapdragon; bilaterally symmetrical; especially in reference to a flower or corolla; Opposite is Actinomorphic; irregular flower;, comprising 3 carpels that are basally attached. The fruits of Myrothamnaceae are three-lobed capsules; dehiscent. Ressurection plant generally undergoes wind pollination.

    Gunnerales Family Differences

    Gunnerales Family Differences

    Gunneraceae

    Gunneraceae

    • Members are perennial herbs. The plants prefer humid habitats.
    • The stems are stout and pachycaulous (not markedly diminished in thickness). The leaves surround the stem. Some species of this family possess huge leaves.
    • The plants have well-developed hydathodes.
    • Gunneraceae are in an endosymbiotic relationship with the genus Nostoc cyanobacteria. They host cyanobacteria on the specialized organ on their stem. The leaf-like scales cover these organs.
    • The flowers of the species are small, simple, and dimerous.
    • The fruit is drupaceous.

    Myrothamnaceae

    Myrothamnaceae

    • Members are glabrous, aromatic, and dioecious shrubs. They are xerophytes.
    • The leaves are small, sessile, opposite, and can survive intense dehydration.
    • The plants have poorly-developed hydathodes.
    • The flowers are tiny, hypogynous, and sessile. The tepals consist of 0-4 or more present in catkin-like inflorescences.
    • The pollen of the members is dispersed as tetrads.
    • The fruit is a capsule with numerous seeds.

    Gunnerales Example Species

    Gunnerales Example Species

    The members of order Gunnerales are beneficial. The following are the example species under this order:

    • Chilean rhubarb[6] is a trendy ornamental plant in gardens and parks. The stalks are edible.
    • Dinosaur food[7] – The plant is used for gardens and landscaping.
    • Devil’s strawberry[8] – The species is an ornamental plant used as a groundcover or planted in the garden.
    • Groundcover gunnera[9] – This species can be used as ground cover, but it can spread undesirably (invasive).
    • Poor man’s umbrella[10] – The plant has ornamental value because of its huge leaves and pretty red veins.
    • Creeping rhubarb[11] is used as a groundcover and a garden plant.
    • Wild rhubarb[12] – The plant has many medicinal uses. The petioles and the flowers stalks can be eaten raw.
    • Resurrection plant – The plant is essential in Africa because of its medicinal value.
    • Myrothamnus moschata
    • Gunnera bogotana

    Cite This Page

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    BioExplorer.net. (2022, August 10). Order Gunnerales / Rhubarb & Resurrection Flowers. Bio Explorer. https://www.bioexplorer.net/order-gunnerales/.
    BioExplorer.net. "Order Gunnerales / Rhubarb & Resurrection Flowers" Bio Explorer, 10 August 2022, https://www.bioexplorer.net/order-gunnerales/.
    BioExplorer.net. "Order Gunnerales / Rhubarb & Resurrection Flowers" Bio Explorer, August 10 2022. https://www.bioexplorer.net/order-gunnerales/.
    Key References
    • [1]“Gunnerales”. Accessed January 15, 2022. Link.
    • [2]“Gunneraceae Meisn. | Plants of the World Online | Kew Science”. Accessed January 15, 2022. Link.
    • [3]“Myrothamnaceae – The Plant List”. Accessed January 15, 2022. Link.
    • [4]“The Gunnera Flower: Key to Eudicot Diversification or Response to Pollination Mode? on JSTOR”. Accessed January 15, 2022. Link.
    • [5]“Myrothamnus flabellifolius | PlantZAfrica”. Accessed January 15, 2022. Link.
    • [6]“Chilean rhubarb (Gunneratinctoria): biology, ecology
      and conservation impacts in New Zealand”
      by Peter A. Williams, Colin C. Ogle, Susan M. Timmins, Graeme D. La Cock and Jim Clarkson. Accessed January 15, 2022. Link.
    • [7]“Gunnera manicata – Plant Finder”. Accessed January 15, 2022. Link.
    • [8]“Gunnera magellanica | devil&s;s strawberry Alpine Rockery/RHS Gardening”. Accessed January 15, 2022. Link.
    • [9]“Gunnera monoica (Groundcover Gunnera) – Keeping It Green Nursery”. Accessed January 15, 2022. Link.
    • [10]“Poorman’s Umbrella (Gunnera insignis) – JungleDragon”. Accessed January 15, 2022. Link.
    • [11]“Gunnera prorepens flavida Creeping rhubarb Creeping Care Plant Varieties & Pruning Advice”. Accessed January 15, 2022. Link.
    • [12]“Gunnera perpensa | PlantZAfrica”. Accessed January 15, 2022. Link.

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