Fossils of isolated land plant spores (Heckman et al, 2001) suggest land plants may have been around as long as 475 million years ago; Fossils of land plant spores within plant fragments (Wellman et al., 2003) date back to 425 million years ago ( these were found in Oman and appear to be liverwort-like, although elaters are noticeably absent!)
The noun PUPILLARY REFLEX has 1 sense: 1. reflex contraction of the sphincter muscle of the iris in response to a bright light (or certain drugs) causing the pupil to become smaller. Familiarity information: PUPILLARY REFLEX used as a noun is very rare. Dictionary entry details.
A reflex is an automatic response to a stimulus. Humans use reflex  actions in only some of their behaviour, for example controlling  the eye's pupil size. Simple reflexes. â¦ Simple reflexes produce  rapid involuntary responses to a stimulus. reflex is a quick involuntary action. There are five steps to a reflex: the stimulus occurs, the sensory neurons sense the stimulus, it sends a message to your spinal cord (â¦ it doesn't reach the brain right then), the spinal cord sends a message to your motor neurons, and the reflex occurs.