Play this movie a couple of times. After watching the propagule at the front, watch the dead one (same orientation, second box).
Supplementary movie 2 - diageotropic curvature - During the second phase of sprouting, push-ups are replaced by increasing hypocotyl curvature which does not completely relax at night. The dead propagule does not enter this phase.
Note that restrained propagules (the third from the front) nonetheless curve. The epicotyl-less propagule toward the rear lifts (delayed push-up phase?) but does not curve.
Supplementary movie 3 - basal curvature and elevation - During the third phase of sprouting, a second center of curvature develops at the base of the propagules, just above the point where roots anchor them. This elevates the whole unit distal to the base.
Restrained propagules (the third from the front) continue to curve. No lifting of the base is visible yet, however. The epicotyl-less propagule toward the rear lifts higher, but with minimal curvature.
Supplementary movie 4 - autotropic straightening (and leaf emergence) - During the last phase of sprouting, the elevated propagule straightens as it becomes vertical. This is accomplished by elongation of the inner radius of curvature. At this point, too, the epicotyl bud swells and the shoot emerges... this is NOT developmentally linked to the elevation itself (see main text).
At this point, the epicotyl-less propagule has developed an adventitious bud. In general, mangroves do not retain the capacity for that for very long. The restrained propagules also develop leaves and begin to pull their bases from the soil (it is a bit hard to see).
Supplementary movie 5 - composite of all four phases - This movie combines all four phases into a single, summarizing movie
And for your total viewing pleasure, the full Monty... all four phases along with a brief intro and ¡Music!