MILEPOST 12 / UPPER DRY CREEK WILDFLOWER WALK
mid June to mid July

Ponderosa Pine Overlook in Upper Dry Creek.

Enjoy spectacular mountain flowers and views along the Upper Dry Creek trail system from the Milepost 12 trailhead at the lower edge of the conifer forest, 2500 feet above the Boise Valley heat.  This is the quickest driving access to a hike in the conifers for most residents of Boise, with the least carbon footprint.  In addition to penstemon and other showy floral treasures, special treats of  this wildflower walk include two native (albeit inconspicuous) orchids and several types of parasitic plants.

Description: The Upper Dry Creek trail system is on private land owned by the Grossman Family, with public access made possible (at least for now) thanks to a partnership with the Land Trust of the Treasure Valley and Ridge to Rivers.  The wildflower walk begins at the side road taking off from the dogleg on Bogus Basin Road just past Milepost 12.  Parking options are informal and very limited, so carpooling is recommended for groups; note that there is also roadside parking for several cars on the opposite side of Bogus Basin Road.  The walk as described (Ponderosa Pine Overlook trail and Snowshow Hare Loop) is about 3 miles long, with about 350 foot elevation gain.  The trails follow old logging roads, mostly fairly level but eroded in places and with some steep sections.

Silver lupine and ragged-robin at Milepost 12 trailhead.

Begin by appreciating the wildflowers on the open sandy roadcuts, starting in the parking area itself.  Among the locally common plants that might be in bloom are ragged-robin (Clarkia pulchella), sticky geranium (Geranium viscosissimum), wand phacelia (Phacelia heterophylla), Payette penstemon (Penstemon payettensis), sulphur buckwheat (Eriogonum umbellatum), common tarweed (Madia gracilis), and large-flowered groundsmoke (Gayophytum diffusum).  Both silver lupine (Lupinus argenteus) and silky lupine (Lupinus sericeus) are present; the former has blue-violet flowers, while the latter has lavendar flowers that turn tan after being pollinated.  Sharp eyes might even spot a small patch of narrowleaf skullcap (Scutellaria angustifolia) tucked under a bittercherry not far from Bogus Basin Road, or an odd-looking buckwheat broomrape (Aphyllon sp. nov., previously in Orobanche fasciculata) parasitizing the roots of the sulphur buckwheat.  Common shrubs at the trailhead include bittercherry (Prunus emarginata), chokecherry (Prunus virginiana), Macdougal’s rose (Rosa nutkana ssp. macdougalii), and Scouler’s willow (Salix scouleriana)

Streamlet at Milepost 12 trailhead.

Take time to look for some interesting plants where a small streamlet flows over rocks, in the bend of the road just before the vehicle gate.  The streamlet and adjacent steep slope is sensitive habitat, so please avoid the temptation to clamber up for a closer peek.  In addition to field monkeyflower (Erythranthe arvensis, previously in Mimulus guttatus), wormleaf stonecrop (Sedum stenopetalum), brittlefern (Cystopteris fragilis), this is an excellent place to see pearlwort (Heterocodon rariflorum), a strong contender for our least visually attractive native wildflower.  The species epithet refers to its rarely produced small blue chasmogamous bellflowers; the plant usually depends instead on inconspicuous self-pollinating cleistogamous flowers.  It is nevertheless one of my favorite plants to find, and maybe you’ll be lucky to catch it with a blue flower or two!  Late in the season, the dried streamlet can be white with the delicate blossoms of mountain or Gairdner’s yampah (Perideridia montana).

Upper Dry Creek forest.

Following the road (DC5) beyond the gate, the vegetation gradually transitions from mid-elevation brushland to a shaded conifer forest, mostly Douglas-fir (Pseudotsuga menziesii) with a few ponderosa pine (Pinus ponderosa).  Shrubs and small trees that make their appearance in the transition zone include snowbrush ceanothus (Ceanothus velutinus), Rocky Mountain maple (Acer glabrum), mountain snowberry (Symphoricarpos rotundifolius var. vaccinioides), mallowleaf ninebark (Physocarpus malvaceus), and even a few quaking aspen (Populus tremuloides), among others.  One noteworthy roadside rosebush differs from the locally common solitary-flowered Macdougal’s rose (Rosa nutkana ssp. macdougalii) in having multiple flowers; it is probably a natural hybrid between Macdougal’s rose and interior rose (Rosa woodsii ssp. ultramontana), which is the common native rose below the conifer zone.  The partly shaded roadbanks provide habitat for an increased diversity of wildflowers, notably Wilcox’s penstemon (Penstemon wilcoxii), branched phacelia (Phacelia ramosissima var. subglabra), diamond-petal farewell-to-spring (Clarkia rhomboidea), scarlet gilia (Ipomopsis aggregata), and western sweet-cicely (Osmorhiza occidentalis).  A colony of horsemint (Agastache urticifolia) can be spotted (and smelled) at one bend in the road, while a patch of thimbleberry (Rubus nutkanus, previously R. parviflorus) grows at a brushy streamlet.

Junction of Ponderosa Pine and Snowshoe Hare Loop trails.

Keep to the left at unmarked junctions until reaching the intersection with the Snowshoe Hare Loop (DC4) at about 3/4 mile from the trailhead.  To follow this wildflower walk as described, take the left-hand fork and do the loop in a clockwise direction.  The road winds its way up the slope, with an abundance of sheltered north- and east-facing slopes in relatively dense forest.  This is excellent habitat to look for the slender spires of Alaska rein-orchid (Platanthera unalascensis), a true native orchid that is fun to find even though the tiny green flowers are not particularly showy.  Be sure to also peek under roadside thickets of Scouler’s willow (Salix scouleriana) for the distinctively mottled leaves of rattlesnake-plantain (Goodyera oblongifolia), another native orchid; the spikes of cream-colored flowers generally don’t develop until mid-summer.  You might also notice the sweetly scented leaves of fragrant bedstraw (Galium trifolium) in the same habitat, more restrained than its rambuctious relative common bedstraw (Galium aparine).   Sections of this loop are also brightened by large roadside stands of Idaho woodbeauty (Drymocallis glabrata), and if the timing is right (mid-summer), you can enjoy the lovely mountain hollyhock (Illiamna rivularis).

Field dodder
Western dodder (Cuscuta occidentalis)

Snowshoe Hare Loop levels out for a while, before intersecting Doug Fir Trail (DC3).  Turn right to continue on Snowshoe Hare Loop, down a fairly steep grade that can be slippery in spots.  The road cuts through a dense thicket of snowbrush ceanothus (Ceanothus velutinus), whose white flower clusters and shiny resinous leaves can scent the air on a sunny day.   Midway down the slope is a flat opening, possibly an old logging staging area, with abundant large-flowered groundsmoke (Gayophytum diffusum), common tarweed (Madia gracilis), and other annuals.  In the center of the clearing are several large clumps of mountain stinging nettle (Urtica dioica ssp. gracilis); note the sharply toothed leaves and dangling inflorescences of tiny flowers, so you know what to avoid.  Some of the rubber rabbitbrush (Ericameria nauseosa) at the lower edge of the clearing are unwilling hosts to tangled orange threads and small white flowers of western dodder (Cuscuta occidentalis), a native parasitic plant. 

Pinedrops (Pterospora andromedea)

Ponderosa Pine Overlook is  at the bottom of the grade, where Snowshoe Hare Loop reconnects with Ponderosa Pine trail.  Several large boulders, scenic views, and a shaded flat opening make this site a destination point and pleasant place to take a break.  A few hotrock penstemon (Penstemon deustus) grow among the boulders, but the flowers tend to finish blooming fairly early.  Turn right on a well-shaded road to return to complete the loop and return to the trailhead, keeping a sharp eye out for more Alaska rein-orchid and, if you are lucky, some pinedrops (Pterospora andromedea) in the open forest floor.   This curious plant, which lacks chlorophyll, has traditionally been categorized as a saprophyte, meaning a plant that obtains its nourishment from decomposing vegetation.  It is now better interpreted to be a freeloader on the forest’s intricate mycorrhizal network that connects fungal mycelium and tree roots.  The mycelium effectively extends the nutriet and water collecting capacity of the tree roots, while obtaining photosynthetic nourishment produced by the tree; as far as is known, supposed “saprophytes” like pinedrops also tap into the network for their nourishment, but provide nothing in return.

Musk monkeyflower (Erythranthe moschata)

Once back at the trailhead, there is the option of a few bonus wildflowers by walking up Bogus Basin Road a couple of hundred feet to a roadside wet spot where a streamlet intersects the road.  There are good-sized patches here of musk monkeyflower (Erythranthe moschata, previously in Mimulus), with its unusual slimy hairs, and American speedwell (Veronica americana).  There might even be some flowering stalks of white bog-orchid (Platanthera dilatata), a much showier species than the Alaska rein-orchid.

 

PLANT LIST [updating needed]

NOTE: Please enjoy the wildflowers and leave them for others to enjoy.  Because our unique local flora is already under pressure from invasive weeds and habitat loss, harvesting of native plants is not encouraged on this website, especially along popular trails.

Plants listed alphabetically by genus within category. * indicates native species

Download plant list pdf

WILDFLOWERS

FERNS AND RELATIVES

SHRUBS AND TREES (not all in bloom)

SIGNIFICANT NOXIOUS WEEDS (some not yet in bloom, but evident)

OTHER GRASSES & GRASSLIKE PLANTS