Evolution Due to environmental factors, It may not look it, but, needles are leaves, they collect solar radiation to produce glucose through the process of photosynthesis, however, needles are, some would say, evolutionary superior to leaves. Needles themselves hold in more water due to their dense wax coating, they are very difficult for insects and other organisms to eat, one because of their structure, and two because of their acidity, they can catch sunlight all year long due to their winter resilience( they don't fall, during the winter), and they have less surface area for wind to catch, which leaves them better protected from wind than most deciduous trees, however the surface area can also pose a larger problem for less surface area means less sunlight interception, therefore more are needed to compete against regular leaves. But.. I Digress... Plant needles are 'PROBABLY' initially the result of evolution of narrow leaves due to climate or environmental factors.
Sry its so long got carried away! Hope this helps xD
Explanation:
Smooth muscle can be found in the walls of hollow organs and passageways, they can contract and they have fibers of actin and myosin tuning though it arranged in an staircase form.
In the images I added you can see how smooth muscle looks when observed in a microscope, wider in the middle and elongated at the ends, and the staircase arrangement.
I hope you find this information useful and interesting! Good luck!
