Gyroscopic stabilization minimizes drag on
            <i>Ruellia ciliatiflora</i>
            seeds

Cooper, Eric S.; Mosher, Molly A.; Cross, Carolyn; Whitaker, Dwight

doi:10.1098/rsif.2017.0901

Cited by 18 publications

(27 citation statements)

References 24 publications

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“…We discuss the presence of a latch system for triggering seed release and emphasize that 'morphological noise' is likely to be responsible for seed rotation initiation. We hypothesize that these features increase the dispersal distance of H. mollis seeds, which may be a selective advantage as an understorey shrub [8,30]. While short-distance seed dispersal is responsible for the local dynamics of plant populations, long-distance dispersal shapes their large-scale dynamics, and both may be important for a plant species to persist (reviewed by Schurr et al [31]).…”

Section: Resultsmentioning

confidence: 99%

“…Plants with ballistochory, i.e. which forcibly eject their seeds, have evolved structural means optimizing the seed launch angle, the release of elastic energy stored in the fruits and the reduction of drag during seed flight [2][3][4][5][6][7][8], leading to further dispersal distances. In witch-hazels (Hamamelis spp., Hamamelidaceae) (figure 1a), the fruits act as 'drying squeeze catapults' [1,9] for shooting the seeds.…”

Section: Introductionmentioning

confidence: 99%

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A seed flying like a bullet: ballistic seed dispersal in Chinese witch-hazel (Hamamelis mollisOLIV., Hamamelidaceae)

Poppinga

Böse

Seidel

et al. 2019

J. R. Soc. Interface.

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The fruits of Chinese witch-hazel ( Hamamelis mollis , Hamamelidaceae) act as ‘drying squeeze catapults', shooting their seeds several metres away. During desiccation, the exocarp shrinks and splits open, and subsequent endocarp deformation is a complex three-dimensional shape change, including formation of dehiscence lines, opening of the apical part and formation of a constriction at the middle part. Owing to the constriction forming, mechanical pressure is increasingly applied on the seed until ejection. We describe a structural latch system consisting of connective cellular structures between endocarp and seed, which break with a distinct cracking sound upon ejection. A maximum seed velocity of 12.3 m s −1 , maximum launch acceleration of 19 853 m s −2 (approx. 2000 g ) and maximum seed rotational velocity of 25 714 min −1 were measured. We argue that miniscule morphological differences between the inner endocarp surface and seed, which features a notable ridge, are responsible for putting spin on the seed. This hypothesis is further corroborated by the observation that there is no preferential seed rotation direction among fruits. Our findings show that H. mollis has evolved similar mechanisms for stabilizing a ‘shot out’ seed as humans use for stabilizing rifle bullets and are discussed in an ecological (dispersal biology), biomechanical (seed ballistics) and functional–morphological (fine-tuning and morphospace of functional endocarps) contexts, and promising additional aspects for future studies are proposed.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A seed flying like a bullet: ballistic seed dispersal in Chinese witch-hazel (Hamamelis mollisOLIV., Hamamelidaceae)

Poppinga

Böse

Seidel

et al. 2019

J. R. Soc. Interface.

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“…For Ruellia ciliatiflora seeds ( Fig. 1d), those released from more distal parts of the fruit are suddenly pulled sideways by the bending of the fruit septa (Cooper et al, 2018). This results in horizontal motion of the curved retinacula that cradle and orientate the round, flattened seeds.…”

Section: Explosive Dispersalmentioning

confidence: 99%

“…This careful orientation during launch produces a backspin on many of the seeds that causes them to spin like a frisbee. The spinning motion gyroscopically stabilizes their flight, leading to reduced drag forces on the seeds and increased dispersal distances compared with seeds that do not spin (Cooper et al, 2018).…”

Section: Explosive Dispersalmentioning

confidence: 99%

From passive to informed: mechanical mechanisms of seed dispersal

Seale

Nakayama

2019

New Phytologist

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SummaryPlant dispersal mechanisms rely on anatomical and morphological adaptations for the use of physical or biological dispersal vectors. Recently, studies of interactions between the dispersal unit and physical environment have uncovered fluid dynamic mechanisms of seed flight, protective measures against fire, and release mechanisms of explosive dispersers. Although environmental conditions generally dictate dispersal distances, plants are not purely passive players in these processes. Evidence suggests that some plants may enact informed dispersal, where dispersal‐related traits are modified according to the environment. This can occur via developmental regulation, but also on shorter timescales via structural remodelling in relation to water availability and temperature. Linking interactions between dispersal mechanisms and environmental conditions will be essential to fully understand population dynamics and distributions.

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“…However, a ridged seed surface may influence seed launch or flight in other ways that affect dispersal. For example, the explosively dispersed seeds of Ruellia ciliatiflora are launched with stabilizing backspin in an orientation that minimizes drag, thereby increasing dispersal range (Cooper et al, 2018;Seale and Nakayama, 2019). Therefore, these questions warrant further investigation in C. hirsuta.…”

Section: Discussionmentioning

confidence: 99%

Seed coat development in explosively dispersed seeds of Cardamine hirsuta

Neumann

Hay

2019

Annals of Botany

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Background and Aims Seeds are dispersed by explosive coiling of the fruit valves in Cardamine hirsuta. This rapid coiling launches the small seeds on ballistic trajectories to spread over a 2 m radius around the parent plant. The seed surface interacts with both the coiling fruit valve during launch and subsequently with the air during flight. We aim to identify features of the seed surface that may contribute to these interactions by characterizing seed coat differentiation. Methods Differentiation of the outermost seed coat layers from the outer integuments of the ovule involves dramatic cellular changes that we characterize in detail at the light and electron microscopical level including immunofluorescence and immunogold labelling. Key Results We found that the two outer integument (oi) layers of the seed coat contributed differently to the topography of the seed surface in the explosively dispersed seeds of C. hirsuta vs. the related species Arabidopsis thaliana where seed dispersal is non-explosive. The surface of A. thaliana seeds is shaped by the columella and the anticlinal cell walls of the epidermal oi2 layer. In contrast, the surface of C. hirsuta seeds is shaped by a network of prominent ridges formed by the anticlinal walls of asymmetrically thickened cells of the sub-epidermal oi1 layer, especially at the seed margin. Both the oi2 and oi1 cell layers in C. hirsuta seeds are characterized by specialized, pectin-rich cell walls that are deposited asymmetrically in the cell. Conclusions The two outermost seed coat layers in C. hirsuta have distinct properties: the sub-epidermal oi1 layer determines the topography of the seed surface, while the epidermal oi2 layer accumulates mucilage. These properties are influenced by polar deposition of distinct pectin polysaccharides in the cell wall. Although the ridged seed surface formed by oi1 cell walls is associated with ballistic dispersal in C. hirsuta, it is not restricted to explosively dispersed seeds in the Brassicaceae.

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Gyroscopic stabilization minimizes drag on Ruellia ciliatiflora seeds

Cited by 18 publications

References 24 publications

A seed flying like a bullet: ballistic seed dispersal in Chinese witch-hazel (Hamamelis mollisOLIV., Hamamelidaceae)

A seed flying like a bullet: ballistic seed dispersal in Chinese witch-hazel (Hamamelis mollisOLIV., Hamamelidaceae)

From passive to informed: mechanical mechanisms of seed dispersal

Seed coat development in explosively dispersed seeds of Cardamine hirsuta

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