Sprays of delicate flowers are dense on a grassy hillsides of Ring Mountain. Pink buds open into slightly disheveled white flowers–the petals are slightly disarranged and appear delicate, as if loosely attached.
This diminutive beauty is Marin dwarf flax (Hesperolinon congestum), which grows only on the Tiburon Penninusla and the San Francisco Peninsula. It is only found on serpentine soils, and can be distinguished from other local types of dwarf flax because the petals are more than 5 mm long, and the sepals are covered with fine hairs. Leaves are small and needlelike.
These amazingly beautiful lilies are in full bloom on Ring Mountain right now–catch them before they are gone! Tiburon mariposa lilies (Calochortus tiburonensis) grow only on the Tiburon peninsula–where they weren’t discovered until 1971, and were listed as Federally threatened in 1995. It grows on Ring Mountain along with several other rare species that are associated with serpentine soils.
This striking lily sprouts a handful of blooms (2-7) on a single stem with a single leaf. The blooms can be brownish, yellowish, or greenish with dense hairs on the inner surface of its three petals. Darker brown markings decorate flowers.
A good place to see these blooms is along the rocky slopes of the western fork of the Phyllis Ellman trail on Ring Mountain, near point-of-interest marker post #14 (this is the westernmost leg of the loop trail; the right-hand fork if you start from the Paradise Drive parking area).
It’s easy to walk right past one of the rarest shrubs in California. Especially at this time of year, western leatherwood (Dirca occidentalis) is little more than a bundle of slim branches hidden in the dappled shade of the forest.
But despite being understated, this is a lovely plant. It produces its leaves and flowers from the same bud. First fuzzy, pussy-willow-type buds pop out all over the multiple, reddish-brown stems that rise from the ground. Then small but intricate yellow flowers emerge–first the long pistil, and then the many drooping stamens. As the flowers fade, the fuzzy young leaves begin to appear. In my limited experience with dirca, as it is often called, these things happen at different times on a single plant so you can see buds, flowers and young leaves all at the same time.
Dirca grows only in the San Francisco Bay Area–and even here it is a very rare sight. It tends to grow on moist hillsides, in partial shade. In the place where I saw one, it was under oaks and alongside hazelnut. The older stems were mottled, splotched with patches of white and gray.
Tiny pale pink flowers are scattered throughout the grasses and serpentine rocks of Carson Ridge. They grow singly and in small clusters at the end of highly branched, wiry stems. When you look close you see that they form a cobwebby network throughout the brown grass. This is Mt. Tamalpais lessingia (Lessingia micradenia var. micradenia).
This plant prefers shallow gravely soil on serpentine outcrops, according to the Marin Flora. This variety grows only in Marin, and is listed as a rare species. It also is very counterintuitive to identify. Though it appears to have single blossoms with five petals, it’s actually in the Asteraceae family along with sunflowers, daisies and other composites. But the Lessingia species tend to be sneaky this way–check out this list and see for yourself.
Mt. Tamalpais jewelflower
On a bare serpentine outcrop high above the Pacific ocean is a low leafless stalk with a few small purple flowers. This is the Mt. Tamalpais jewelflower, a sub-species of Streptanthus glandulosus which is found only in Marin County. Though the plant is unassuming, when you look close the flowers have earned their name. Narrow, crinkled petals flare out above a colorful pouch that is faceted and luminous like a gem.
The jewelflower is in the same family as radish and milkmaid. The long, narrow, fleshy seed pods that are pictured below are typical of the family, though the unusual flowers are not! I saw this beauty, S. glandulosus ssp. pulchellus, near Rock Springs on Mt. Tam during the MMWD/Cal Academy Bioblitz last weekend, and owe thanks for the ID to Terry Gosliner. I wrote about secund jewelflower back in May – which is also a sub-species of S. glandulosus, and the only jewelflower in Marin that isn’t listed as either rare or endangered.
Growing alongside a meadow stream are many spikes of pale flowers. This is marsh zigadene, or Toxicoscordion micranthus. A few long, linear leaves sit unobtrusively at the base of the plant, which is decked with several dozen creamy white blossoms. The six-petalled flowers have a small yellow spot at the base of each grooved petal, and a short tight cluster of stamens with oversized anthers.
Marsh zigadene is a native that is usually found growing in damp places, often near serpentine, according to the Flora of Marin. It’s common in this county but is rare elsewhere.
The common name for the several similar-looking species in the Toxicoscordion genus is “death camas.” These species are another example of highly toxic beauty. I have always known these plants as Zigadenus species, but they were recently moved to a different group (something that is always happening in the botany world – it can be hard to keep track!). They are still listed in most floras under the old name, but are in online databases under the new name.