Species Pinus monophylla

pinyon pine 2-year cone cycle

pinus monophylla small medium size tree, reaching 10–20 m (33–66 ft) tall , trunk diameter of 80 cm (31 ⁄2 in) more. bark irregularly furrowed , scaly. leaves ( needles ) are, uniquely pine, single (not 2 or more in fascicle, though trees needles in pairs found occasionally), stout, 4–6 cm (1 ⁄2–2 ⁄4 in) long, , grey-green glaucous blue-green, stomata on whole needle surface (and on both inner , outer surfaces of paired needles). cones acute-globose, largest of true pinyons, 4.5–8 cm (1 ⁄4–3 ⁄8 in) long , broad when closed, green @ first, ripening yellow-buff when 18–20 months old, small number of thick scales, typically 8-20 fertile scales. cones grow on two-year (26-month) cycle, newer green , older, seed-bearing or open brown cones on tree @ same time (see image @ left).

open cone empty pine nuts

the cones open 6–9 cm (2 ⁄4–3 ⁄2 in) broad when mature, holding seeds on scales after opening. seeds 11–16 mm (⁄16–⁄8 in) long, thin shell, white endosperm, , vestigial 1–2 mm (⁄32–⁄32 in) wing. empty pine nuts undeveloped seeds (self-pollinated) light tan color, while ones dark brown. pine nuts dispersed pinyon jay, plucks seeds out of open cones, choosing dark ones , leaving light ones (as in image @ right). jay, uses seeds food resource, stores many of seeds later use burying them. of these stored seeds not used , able grow new trees. indeed, pinyon seeds germinate in wild unless cached jays or other animals.