Juncus patens,California gray rush, is an adaptable reed that is native to the entire west coast of the U.S. In the wild it is found near seeps, springs, marshes and riparian zones along streams, rivers and ponds. In landscaping the gray rush is often used in rain gardens and phytomediation swales/ponds to filter the water. Since it spreads by rhizomes into substantial clumps, Juncus patens is used extensively in habitat restoration projects. In the BLNPG, it can be seen in the basins of the rain garden near the north entrance, where it helps clean water run-off from the adjacent ball field.

Juncas patens is upright and finely textured, forming dense clumps of narrow blue-gray stems, which grow to a height of 18-24 inches. Its golden-brown flowers appear in clusters from the side of the stems from spring to fall. They develop into brown capsules full of seeds, which are attractive to birds. Although it prefers moisture, California gray rush will grow in dry conditions, as well, and thrives in both sun to part shade. If grown in dry conditions, it will go dormant during the summer and reappear when it rains.