Trees

Division - Coniferophyta - cone-forming seed plants
Pine 
  See Pines in Tahoe
Fir - flat, friendly
Spruce - square, spiney

Look for the number of needles that come out of the same spot on a twig. If a twig bears needles in groups of two, three, or five, you can safely call it a pine. If the twig carries its needles singly, itÕs a good bet youÕve got a fir or a spruce. Pull off a needle, and roll it between your fingers. If it feels flat and doesnÕt roll easily, itÕs a fir. If the needle has four sides and, thus, rolls easily between your fingers, itÕs a spruce.


Cyprus
Cedar
Sequoia

 Pinaceae
   Douglas-fir
   Pine, spruce
Cupressaceae

..White cedar, 

Cupressaceae (Taxodiaceae)

..Sequoia

Cupressaceae

..California redwood

Cupressaceae

  ..Juniper
  ..Eastern red cedar
  ..Bald cypress

Division - Anthophyta - fruit-forming seed plants - flowering plants (angiosperms)
  Deciduous Families
    Aceraceae
      Maple tree
    Betulaceae
      Birch
    Fagaceae
      White oak
    More at Deciduous and Coniferous Trees

Links:
Deciduous and Coniferous Trees
Pines in Tahoe