A broad expanse of gumplant, a hip-high bush bearing leathery green leaves, has not yet sprung its resin-topped flowers at the Giacomini Wetlands. But last Friday, a wetland biologist had no problem explaining what would happen come summer. “It oozes like glue, like Elmer’s Glue,” said John Callaway, a professor at the University of San Francisco who led a two-hour excursion for handful of amateur naturalists last Saturday as part of the seventh annual BioBlitz BioDiversity Festival, a 10-year project leading up to the National Park Service’s centennial in 2016. The 24-hour blitz is held in a different national park each year, with expert scientists leading volunteers to document flora and fauna. This year’s event took place in the Golden Gate National Recreation Area’s lands in Marin and San Francisco, though the Point Reyes National Seashore also participated. So far 2,304 species of plant and animal life—80 of which were new to G.G.N.R.A.’s species list—have been tallied, though the number could increase as more data are analyzed. In the Giacomini Wetlands, the only area in the seashore included in the blitz, 214 species have been counted so far (none were new discoveries). As Mr. Callaway and his group traipsed through the mud on a walk titled “Wildflowers and More,” they identified plants like arrowgrass, curly doc, pickleweed and sea plantain, but not many blooms. Finally, though, a conspicuous yellow one caught the group’s attention. “Our first flower!” a woman cried after spotting a few sunny cinquefoils.