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14.2: Dispersal Mechanisms

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    A cluster of purplish, swollen berries on a small plant lacking chlorophyll, growing out of a pine branchA bird (A) and a seed shooting out from a berry, propelled by a jet of water (B)
    Figure \(\PageIndex{1}\): A cluster of dwarf mistletoe berries (first image). The seeds are shot out (second image, B) when turgor pressure builds up within the berry. Dwarf mistletoe seeds have velocities of about 24 m/s and may travel over 10 meters. The seeds are covered with a sticky substance (viscin) and occasionally are dispersed by birds, either by being eaten or getting stuck to them. First image by Maria Morrow, CC BY-SA 3.0. Second image from the open-access paper Mistletoes: Pathology, Systematics, Ecology, and Management (Mathiasen et al. 2008), Plant Disease.
    A dwarf mistletoe seed
    Figure \(\PageIndex{2}\): "The sticky seed of juniper dwarf mistletoe (Arceuthobium oxycedri (DC.) M. Bieb) from the Crimean Peninsula ̶ a semi-parasitic species of Holarctic Cupressaceae hosts parasitizing Eastern prickly juniper, Juniperus deltoides R.P. Adams, Greek juniper, J. excelsa M. Bieb. and Oriental thuja, Platycladus orientalis (L.) Franco. Among the unique features of Arceuthobium spp. are ballistic seed dispersal primarily achieved through a hydrostatically controlled explosive discharge mechanism and thermogenesis. Seeds of A. oxycedri are ~0.9−1 mm long and ~0.4−0.5 mm wide, with an elongated pedicel on the proximal (acuminate) apex. A. oxycedri seeds are covered by a sticky viscin (“birds glue”) forming a snow-white cap on the distal (roundish) apex and thin layer on the surface of the seed. After the hydration viscin forms sticky stands required for parasite attachment to the host branch and/or sporadic ornithochory. The picture was taken using stereomicroscope Axio Zoom.V16 (Carl Zeiss, Germany). Seeds are from Mt. Malyi Sokol, Sudak territory Autonomous Republic of Crimea, Ukraine." Image and caption text by Yuliya Krasylenko, CC BY-SA 4.0 via Wikimedia Commons.

    Video \(\PageIndex{1}\): Watch this fun video of different plants utilizing ballistic seed dispersal. Sourced from YouTube.


    Four sets of paired seeds (maple "helicopters" or fruits), each seed has a long flat wing attached to it. Two dangling seeds, each with four flat sail-like wings attached
    Figure \(\PageIndex{3}\): Samaras are winged achenes adapted to wind dispersal. The maple samaras in the first image are also schizocarps, breaking apart at maturity into two separate fruits. First image by Gmihail at Serbian Wikipedia, CC BY-SA 3.0, via Wikimedia Commons. Second image by Marco Schmidt [1], CC BY-SA 3.0 via Wikimedia Commons.


    A lotus fruit. A cup-like structure with many seeds embedded within it.
    Figure \(\PageIndex{4}\): Lotus seeds are water dispersed. This lotus fruit is bouyant and has many seeds embedded within it. As it matures, it dries, the seeds are released and sink into the water to germinate. Photo by Bouba, CC BY-SA 3.0 via Wikimedia Commons.

    Video \(\PageIndex{2}\): Watch this clip to see more water-dispersed seeds and fruits. Sourced from YouTube.

    Animal Attachment & Ingestion

    Several spiky, dry fruits about 2 cm long
    Figure \(\PageIndex{5}\): Animal attachment. Fruits of Xanthium, cockleburrs, have hooked spikes that allow them to attach to passing animals. Photo by Muséum de Toulouse, CC BY-SA 3.0 via Wikimedia Commons.
    a cluster of red fruits: aggregates of druplets known as raspberries
    Figure \(\PageIndex{6}\): Animal ingestion. Fruits that we think of as fruits are generally adapted for animal ingestion. These red raspberries might be eaten by birds, the seeds excreted in some new locale. Photo by Juhanson, CC BY-SA 3.0 via Wikimedia Commons.
    A bright red chile pepper
    Figure \(\PageIndex{7}\): Habanero chiles (and other spicy peppers) have specially adapted for bird dispersal. They contain a compound called capsaicin that is incredibly spicy to most mammals but does not bother birds. Photo from The original uploader was Fir0002 at English Wikipedia., CC BY 2.5 via Wikimedia Commons.

    This page titled 14.2: Dispersal Mechanisms is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Maria Morrow (ASCCC Open Educational Resources Initiative) .

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