Late Summer Bloomers

September 6, 2021

Three bunches of this showy perennial appeared suddenly in the southeastern corner of the park, rising from trampled grasses in a neighborhood of weeds. They are said to be common in Western North America as far as the Dakotas. They’ve not been reported in the park before. Possibly they’re a sleeper from the wildflower seeding that the Conservancy organized in October 2019, when a group of Cal students popped a native wildflower seed mix into the then bare soil that the rip-rap construction job had left in the area. But this plant was not among the crop of pretty blooms that greeted the springtime sunshine in 2020. If it came from that seed mix — where, as a non-native, it would have been a stowaway — it waited 22 months to show itself. By this time, weeds had smothered whatever the ground squirrels hadn’t munched, and the area had reverted to its pre-construction state. All the greater the pleasure to see this uninhibited bloomer there.

Among the other late summer bloomers that greeted park visitors were these regulars:

Bristly Oxtongue (*Helminthotheca echioides)*

The flower of this well-established weed could be confused with dandelion or some other members of its Asteraceae family. The giveaway to its nature is the leaves and stems: spiny and bristly, as the name suggests. It’s listed as an invasive with a “Limited” rating from the California Invasive Plant Council. This individual grows on the north side of the park in the mowed strip next to the paved perimeter trail, but you can find them abundantly wherever the Park mowers regularly graze. When nature is left alone, native plants yield little elbow room to this Mediterranean import, but where the mower decapitates native growth, this spiny weed thrives.

Some botanical immigrants make important contributions to the habitat. An outstanding example is Foeniculum vulgare, the common sweet fennel that grows in thick stands in the northwest corner and parts of the western ridge. In flower since late July, this fragrant long-term resident is the polar opposite of invaders like acacia that local pollinators shun. Fennel is a pollinator magnet. It hosts a species of butterfly, the Anise Swallowtail. Several kinds of bees and pollinator flies regularly visit the feast of pollen and nectar that fennel offers when in bloom. Then the blooms close and turn to seeds, and the fennel heads become a seasonal cornucopia for birds, lasting well into the winter. Our local finches and visiting Red-winged Blackbirds regularly refuel here, and many of the sparrows.

Sweet fennel (*Foeniculum vulgare*) hosting pollinator, probably Western honeybee (*Apis mellifera*)

The Birdsfoot Trefoil patches growing in the meadow below the Native Plant Area also stayed in bloom during this cool and cloudy August month, when the sea air brought plenty of water vapor to the land’s western edge. This is another import that’s well established in the park and has attracted some insect followers, notably the Yellow-faced Bumblebee, as in the photo below:

Birdsfoot Trefoil (*Lotus corniculatus*) visited by Yellow-faced Bumblebee (*Bombus vosnesenskii*)

Another steady bloomer through August is the Gumplant or Gumweed (Grindelia stricta). This California and West Coast native thrives in terrible soils with salt spray and chill winds. It grows between the rip-rap and the trodden footpath on the west edge of the park, about as hostile a habitat as you could find. The “gum” in its name comes from the pool of white latex that the flowers develop as they emerge from the bud. The latex disappears when the flower is in full bloom. The plant hosts least ten species of California butterflies and moths as well as a variety of bees. None of the above happened to be visiting as I snapped the photo.

Not to be left out from a survey of late summer bloomers is the ubiquitous Wild Mustard (Sinapis arvensis). Another import from the Mediterranean, it has been thriving in the park for decades. At least two species of butterfly lay their eggs on it and various bees and flies serve it as pollinators.