Dispersal! Ken Robertson! Illinois Natural History Survey! Syndromes!

Transcription

1 Dispersal! Ken Robertson! Illinois Natural History Survey! Reproduction! There are two critical stages in the life cycle of a flowering plant:! Pollination the transfer of pollen from anther to stigma. Most flowering plants have different types of mechanisms to promote the transfer of pollen from an anther in one flower to a stigma in a different flower, and hopefully this flower will be on a different plant.! Dispersal the dispersal of seeds away from the parent plant.! Plants often solicit the aid of animals or wind to accomplish both of these.! Reproduction! Sexual reproduction is just as important for plants as it is for animals when it comes to generating genetic variation, but plants have a singular disadvantage compared to animals with it comes to sex: they can t just get up and find themselves a mate. May Berenbaum, Bugs in the System! And the seeds can t walk/slither/swim/fly away from their parents.! Why is Dispersal Important?! Avoid competition with parent and siblings! Colonize new habitats! Avoid pathogens and predators! Minimize inbreeding! Syndromes! As with pollination, there are various syndromes of dispersal mechanisms, each syndrome with a suite of similar characteristics that aid in dispersal.! Again, there are two main categories abotic (wind and water) and biotic/animals. There are also a significant number of plants with self-dispersal mechanisms.! Syndromes! Insects much less important for dispersal than! pollination, but ants often involved in dispersal! birds, mammals, reptiles, and even fish much more!important for dispersal than pollination! wind important in both pollination and dispersal! water minor importance in pollination, somewhat!!greater in dispersal! self dispersal just like some plants carry out self!pollination, some plants have mechanisms for self!dispersal.! 1!

2 Syndromes! Methods of dispersal are often tied to certain habitats! Wind prairie/grasslands, mountains, forest trees, weedy!areas! External attachment to animals forest plants relatively!low to ground! Ingestion by animals forest plants! Water plants that grow in wetlands and along streams! Ballistic various; some parasitic plants, some forest!plants, some weedy plants! Units of Dispersal Different plant parts become modified for dispersal.! Seeds released from the fruits! Fruits, or parts of fruit! Units! Other structures sometimes modified for dispersal:!!ovary wall, style, sepals, hypanthium, receptacle,!bracts, even whole plant.! The term DIASPORE is used for the unit of dispersal, no!matter what it is morphologically,! Dust-like seeds! Tiny seeds! winged seeds! samaras! winged bracts!!plumed diaspores! "!Woolly diaspores!!plumed diaspores! "!! 2!

3 !Plumed diaspores! "!Woolly diaspores! balloon fruits! "roller plants! Splash cups! Sea currents! 3!

4 Streams! Streams! Simple adhesion mucilaginous when wet! Simple adhesion, viscin threads! 4!

5 Sock Removal Difficulty Unit (SRDU)! "Carrying & caching! 5!

6 "Ants (elaiosomes)! 6!

7 Ballistic fruits! Ballistic fruits! Dodo bird, Mauritius! Ballistic fruits! Hygroscopic! "Shaker fruits! 7!