The Evolution of Plants. Bryophytes, Lycophytes Botany 4 Lecture #33 The Evolution of Plants. Bryophytes, Lycophytes

Kingdom: Plantae Appeared on land ~ 500 MYA. (How??) Evolutionary history of Plant Kingdom reflects increasing adaptation to terrestrial environment.

Closest Algal Relatives: Charophytes

Plants and Green Algae Share at least 3 characteristics: Chloroplasts w/ Chl a, b and carotenoids. Cellulose cell walls. Food reserves stored in plastids.

terrestrial organisms. Plants transformed the The first truly terrestrial organisms. Plants transformed the nature of life on earth. ???

Comparison of Conditions in the ocean and on land? How did the adaptations to a terrestrial environment drive plant evolution?

As plants evolved on land, they adapted with complex bodies with cell specialization for different functions. Cuticles and stomata to prevent desiccation. Protection for gametes and embryos. Vascular tissue to transport water, minerals, and food.

During the course of Plant evolution… The dominant generation gradually changed from gametophyte to sporophyte…

Bryophytes: First Plants to Conquer Land 3 Phyla: Mosses, Liverworts, Hornworts No roots, stems, leaves or wood. Not tall, tend to sprawl like a mat. Homosporous (Only one type of spore) Gametophyte generation dominant to sporophyte. Sporophyte lives on gametophyte.

Lycophytes 3 Groups: Club Mosses, Selaginella, Isoetes. Simple leaf design. (Microphylls) Most homosporous. Beginnings of heterospory. Extinct Tree forms in Carboniferous (Coal Age) Low modern forms.

Extinct Lycophytes Lepidodendron (Scale Tree) Sigillaria

Lycopodium: Club Moss