Male cone of Pinus
The yellow structures are the male cones of Pinus. They are found at the base of a new shoot. After they have released all of their pollen they wither and will eventually fall off. Pollen and seed cones are often found on the same plant, but rarely on the same shoot.
Here is a close-up of a cluster of pollen (male) cones.
A closer look:
Pinus male cone in longitudinal section
The pollen cone is bascially a modified branch. The leaves are microsporophylls. These modified leaves bear microsporangia which ultimately produce pollen grains. On the right is a closeup view of a longitudinal section through part of a male cone. Note the microsporangia which are found on the abaxial side of the microsporophyll. Each sporangium contains lots of little dots which are the pollen grains.
This is the microsporophyll. You can see on the left that there are two microsporangia per sporophyll. The left microsporangia in the photo is oriented so the top of the microsporophyll is viewed. The one on the right is upside down. The photo on the right is an lateral image of the entire microsporophyll. You can see one of the two microsporangia (pollen sacs) filled with bright yellow pollen grains.
Here is a pollen grain of pine. This species has air bladders. The mature pollen grains of many conifer species do not have air bladders.
Male cones of other conifers
Chamaecyperis lawsoniana
Calocedrus (incense cedar)
Taxus (yew)
Juniperus (juniper)
REPRODUCTION INTRO
MALE CONES
FEMALE CONES
EMBRYO
PINE LIFE HISTORY IN MORE DETAIL