This tall reed rustles its leaves above a small pond. Long cylindrical flower heads look like two plump brown sausages on a spit. The sausages are actually flower heads, with the female flowers clustered in the lower, plumper segment while the male flowers are clustered together above.
These are narrow leaf cat-tails, a common sight in wetlands or roadside ditches. There are actually three species here in the Bay Area that hybridize with one another; the main way to tell them apart is by the flower heads (if the skinnier flower head is stacked immediately above the fatter one with no gap of stem visible in between, you’re looking at common cattail, or Typha latifolia). The two species of narrowleaf cattail (T. domingensis and T. angustifolia) are harder to tell apart–look for orange or yellow flowers, and dark dots on the inside of the lower leaf, to ID T. domingensis.