Noticed blooming in December and January; I’ve only seen it blooming at Hendry’s Beach and the Turnpike bioswale (both marsh places, one brackish), but there are a large stands of it (without blooms) in the creek on the trail between the Grotto and Mono and near the bridge on Romero.
Male flowers look similar to those of Coyote Bush. This plant has much longer and (relatively) thinner leaves and the leaves are much closer to being smooth.
Male and female flowers are quite different and any plant will only produce flowers of one sex. Male (staminate) flowers are traditional disk flowers (white) with very obvious stamens, while female (pistilate) flowers have no stamens.