Blackbrush is a native, aromatic shrub with soft wood [109], growing from 1 to 6 feet (0.3-2 m) tall [16,27,38,79,84,85,90,117,123]. It shows compact, erect growth, with a symmetrically round form [16,118]. The scientific name refers to the unusual sheath or torus around the ovary (Coleogyne) and to its many-branched morphology (ramosissima) [17]. The common name is derived from the color of the dense branches, which have gray bark that turns black with age or when wet [8,16,17,90]. The terminal branches grow for a few years then die, drying back for several centimeters from the tip and resulting in the characteristically tangled spinescence of blackbrush [16,17,79,84,85]. Apical dominance is removed when the terminal buds die, allowing development of lateral branches [16,78,79,84,85]. The shrub undergoes stem-splitting, in which the main stem splits into several smaller portions [16,17]. These clusters of multi-stemmed segments also correspond to separate segments of the root system [118].
Blackbrush has a diffuse and shallow root system [63]. The greatest root biomass of blackbrush is found at a soil depth of 4 to 12 inches (10-30 cm), with few roots penetrating the fractured caliche layer, if present [16,79,84,85]. Large supporting roots are located directly beneath the plant, and root biomass tends to decrease with increasing distance from the plant and with increasing soil depth [79,84,85]. Shallow soils often result in a low root:shoot ratio and limited root development in blackbrush communities [58].
Blackbrush is evergreen [1,27,79,84,85,89,94,109], though it may lose substantial leaf area during the dry summer season [96]. Blackbrush is drought-deciduous, avoiding water stress by becoming temporarily dormant and shedding older leaves as stress intensifies during the dry season [54]. After leaf drop, it enters a long summer dormancy [54]
Atypical of the rose family [8,17], blackbrush flowers typically lack petals [38,68,90,123]. Blackbrush flowers are perfect, solitary, and terminal on the young branchlets [16]. The fruits are dry, leathery achenes, 3 to 4 mm long, with a bent and twisted style [38,90,117].
Blackbrush has a "long" life span [92,121], and its life history emphasizes maintenance of existing individuals; establishment from seed is rare [121]. Blackbrush-dominated stands are generally monotypic, simple communities where shrub cover is high. Close spacing permits little growth of other vegetation [8,16,17,41,45,58,79,84,85,94].
Blackbrush stands are subject to fire [89], and fire will start and spread easily due to the dense, close spacing, "tinder-like" nature, and resinous foliage of blackbrush [17,116,124,125]. There are usually few forbs or grasses in blackbrush stands that might aid in carrying fire, but despite this, blackbrush communities burn under conditions of high temperature, high wind velocity, and low relative humidity [42,72]. Fire also occurs in blackbrush stands on sites with high proportions of herbaceous perennial species or in years in which annuals are abundant [17]. Blackbrush's often strong association with red brome and cheatgrass may result in higher fire frequencies than would occur without the bromes: the grasses leave dense, persistent dead stems that promote fire spread [43]. Various sprouting shrubs and annuals establish after fire, and once these species gain dominance the recurrence rate for fire increases [125]. The presence of Joshua trees in blackbrush stands may also contribute to increased fire frequencies due to lightning strikes on the Joshua trees [43].
Because blackbrush is a nonsprouter, very susceptible to fire, and slow to reinvade sites, it is removed by fire [17,128], and succeeding communities are variable [17]. Fire in blackbrush stands in southwestern Utah resulted in a variety of species dominating the postfire vegetation [3,17]. These postfire dominants include turpentine bush, desert bitterbrush, desert almond, big sagebrush, and some nearly monospecific stands of broom snakeweed [17]. Grasses are more abundant in burned blackbrush communities [116], and burning may improve forage productivity [128]. One 10-year-old burn in blackbrush was devoid of blackbrush and dominated by brittlebrush and desert mallow, with a denser cover of red brome and cheatgrass compared to exotic brome cover in the adjacent unburned blackbrush community [97]. In another study of burned blackbrush sites in southwestern Utah, most shrubs were removed by fire. In the 1st postfire year, forbs greatly increased and grasses moderately increased. Forbs steadily decreased over time, approaching prefire levels, while grasses steadily increased, peaked at postfire year 6, and then declined to prefire levels. Shrub dominance on these sites returned within 20 years, but shrub composition after burning only slightly resembled composition before fire. Blackbrush cover was greatly reduced on all sites. Cryptogamic soil crusts associated with blackbrush communities were also strongly affected by fire. Before burning cryptogamic crusts contributed 9% of plant cover but were reduced to less than 1% of total plant cover after fire. There was very little evidence of crust formation after 19 postburn years [24]. Fire has promoted succession to grassland by destroying the cryptogamic crust, which stabilizes the soil [72].
FIRE REGIMES:
Blackbrush fire regime: The blackbrush association is composed of dense to scattered low-stature shrubs and dense to open grasses, and it maintains the highest cover of any desert shrub community. Blackbrush experiences a stand-replacement fire regime, though historical documentation of blackbrush fire cycles is limited. Frequent large fires have eliminated blackbrush from some areas. Fuel production in blackbrush ranges from 250 to 500 lbs/acre, and blackbrush is negatively associated with fine fuels of litter and grasses. Blackbrush occurs in areas with approximately 7 inches (180 mm) of annual precipitation, and cyclic desert precipitation above 10 to 14 inches (250-360 mm) may increase biomass and fuel continuity enough to increase fire behavior potential [72].
The following table provides some fire regime intervals for ecosystems where blackbrush occurs. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Community or Ecosystem Dominant Species Fire Return Interval Range (years) basin big sagebrush Artemisia tridentata var. tridentata 12-43 [91] Wyoming big sagebrush A. t. var. wyomingensis 10-70 (40*) [115,130] saltbush-greasewood Atriplex confertifolia-Sarcobatus vermiculatus desert grasslands Bouteloua eriopoda and/or Pleuraphis mutica 5-100 grama-galleta steppe B. gracilis-P. jamesii cheatgrass Bromus tectorum mountain-mahogany-Gambel oak scrub Cercocarpus ledifolius-Quercus gambelii blackbrush Coleogyne ramosissima Arizona cypress Cupressus arizonica Rocky Mountain juniper Juniperus scopulorum creosotebush Larrea tridentata pinyon-juniper Pinus-Juniperus spp. Colorado pinyon P. edulis 10-49 Arizona pine P. ponderosa var. arizonica 2-10 galleta-threeawn shrubsteppe Pleuraphis jamesii-Aristida purpurea mesquite Prosopis glandulosa oak-juniper woodland (Southwest) Quercus-Juniperus spp. 22] *meanFires may increase species diversity, livestock carrying capacity, and range condition. The following table describes 5 different sites and improvement of range condition after fire. All sites had cobbled, stony soils with 35% or more gravel content and received a mean annual precipitation of 125 mm [8].
Carrying capacity (acres/AUM & condition)
Name of burn Year Acres Current vegetative composition Prefire Postfire Soil texture Oak Creek unknown 202.5 blackbrush, rabbitbrush, needle-and-thread grass, green ephedra 350/poor 37/fair loam Independence unknown 202.5 Big sagebrush, green ephedra, CA. buckwheat 350/poor 21/good sand Symmes Creek 1 unknown 252.5 CA buckwheat, needle-and-thread grass 88/poor 15/poor loam Symmes Creek 2 unknown 305 CA buckwheat, needle-and-thread grass 350/poor 25/poor sand Symmes Creek 3 pre-1947 650 CA buckwheat, needle-and-thread grass 88/poor 11/poor sand
Prescribed burning on 3 southern Nevada sites killed the blackbrush cover, and the species failed to reestablish after as long as 28 years. Plant succession varied widely, with different plant species dominating on different burns, but the density of annual species was substantially increased in the 1st 3 years following burning. Replacement shrubs after fire were largely undesirable forages [17]. Since sites may be highly suitable for blackbrush, burning these areas to convert them to grassland may give unpredictable or undesirable results [23]. After burning on 3 proximal sites in southwestern Utah, 1 site was dominated by turpentine bush, desert bitterbrush, desert almond, and big sagebrush; another site established a pure stand of broom snakeweed, and a 3rd site established a pure stand of big sagebrush [16]. Vast areas of blackbrush in Nevada were burned in the 1940s and 1950s. These sites were subsequently occupied by annuals and broom snakeweed and have been subject to recurring fires. In wet years, the burned areas had 8 to 10 times more herbage production than the range before it was burned, but herbs were very sparse in dry years [124]. Site potential is an important consideration for burning blackbrush; fire may be more useful on areas with better-developed soils and potential to revegetate to more desirable plants [8]. Widespread burning to reduce blackbrush is not recommended due to the unpredictability of successive vegetation, accelerated soil erosion, long-term or permanent removal of blackbrush, and damage to cryptogamic soil crusts [24,125,129].
Fire may be a necessary tool to modify fuel buildup; however, research is needed regarding management and restoration recommendations for blackbrush [72].
Blackbrush stands occur on well-drained sites including alluvial and colluvial slopes, washes, valley bottoms, lowlands, and flatlands of mild slope, and derived from limestone, sandstone, gneiss, and basalt [1,2,5,6,8,10,15,16,23,47,51,55,58,106,107,118,123,124]. Soils supporting blackbrush are generally shallow, poorly developed, and coarse textured, often with abundant exposed rock and high sand content [5,6,8,17,23,44,51,98,118,123]. These sites are also calcareous, moderately alkaline, and low in salinity [9,17,94,118] with pH ranging from 7.8 to 8.5 [16,17,23]. Blackbrush has a low tolerance for salinity, excessive soil moisture, and impeded soil aeration [124]. Shrubs are often clustered on small mounds, evidently created by entrapment of wind-blown material [121]. There is typically a well-developed microphytic crust on the soil surface between shrubs [125].
The shallowness of soil may in part determine the abundance and distribution of blackbrush [23,55]. Blackbrush is abundant on shallow soils with caliche layers [2,8,12,16,17,23,55,118,125], but is more abundant on adjacent, deeper soils [118]. Blackbrush occurs on ancient granitic debris flows in California, with the cover and density of blackbrush increasing with the age of the debris [120,121]. On the oldest depositional area, blackbrush is nearly monospecific, and the only physical differences between the flows studied are those resulting from difference in geologic age; notably, the intermediate and oldest flows had caliche layers [120,121]. The association of blackbrush with old soils and the lack of it on young basalt flows implies either an allogenically controlled succession with blackbrush dominating [121] or an affinity of blackbrush for calcium carbonate irrespective of the age of the surface [121,125].
Blackbrush individuals alter the soil chemistry around their bases [16,17,121]. Bowns [16] found that percent totals of nitrogen and available phosphorus are higher in soil beneath blackbrush plants than in the spaces between, and both nutrients decrease with increasing soil depth [16].
Blackbrush is not preferred as forage by domestic livestock, deer, or pronghorn, but it does provide poor forage during the spring, summer, and fall for domestic cattle, horses, and domestic sheep [8,19,41,50,90,112,124]. Blackbrush provides poor to good forage for domestic goats [41,84,90]. Mule deer and bighorn sheep generally use the blackbrush vegetation type in winter, and livestock generally use it in winter and spring [17,98,112,124]. The principal forage value of blackbrush appears to be as a browse species for bighorn sheep [17,18,68]; blackbrush communities also provide important habitat for desert bighorn sheep in Nevada [18]. Domestic sheep and goats, and to a lesser extent, cattle browse blackbrush [47,70,118,124]. It provides fair forage for domestic sheep and cattle in the winter in southwestern Utah [17,41], but spiny stems coupled with chemical compounds in current year's growth protect blackbrush from heavy browsing by livestock [6,79,80]. Due to the spinescent growth form of blackbrush, the low amounts of current-season growth are of limited accessibility to most browsing animals [79,112]. Carrying capacities on blackbrush ranges are low, from 30 to 300 acres/AUM [8,124].
Blackbrush often occurs as nearly monospecific stands, with few other forage species available [112]. Though it is not desirable deer forage, in areas where it is extensive it may experience heavy browsing pressure [8,68]. Where it forms an appreciable proportion of the brush cover, it provides a substantial part of the diet of domestic sheep and goats and deer, despite its small leaves and spinescent growth [17]. In California, blackbrush has comprised up to 25% of the mule deer winter diet [52]. Blackbrush-dominated sites where animals congregate may provide inadequate nutrition and impede the regeneration of bitterbrush, a key browse species [8]. The presence of blackbrush in Arizona chaparral may reduce the range quality rating due to its low forage value and exclusion of higher forage value plants [41]. Greater resistance to grazing probably allows blackbrush to persist and perhaps expand after the more palatable species are removed [8].
Small mammals and birds consume blackbrush seeds [68,74,98,124].
In California, blackbrush occurs as a subdominant
species in the Mojave mixed woody scrub, and as a common
understory species in pinyon-juniper (Pinus-Juniperus spp.) woodlands [106].
It is characteristic of the northern desert scrub in Arizona [32,44], and is
dominant in the canyon desert areas of northern Arizona, comprising 90% of the
vegetation in areas where it occurs [87]. Blackbrush is important in the Colorado pinyon
(P. edulis)/blackbrush habitat type in northern Arizona [51]. In Nevada, blackbrush forms a
dominant association [106,125], is a primary shrub associate in the
sagebrush association and the salt desert scrub association, and is a common
associate in the creosotebush-white bursage, hopsage (Grayia spinosa), and Mojave
mixed scrub associations [106]. It is a
subdominant in pinyon-juniper woodlands [4,5,13,21,103,106] and a codominant in stands of Joshua
tree [1,61,77,103] and shadscale [118]. It occurs as a dominant shrub in
both pinyon-dominated and juniper-dominated woodlands, occurring in the
following plant associations [126]:
northern Mojave: singleleaf pinyon (P.
monophylla)/blackbrush/blue grama (Bouteloua gracilis); singleleaf
pinyon/blackbrush/wavyleaf Indian paintbrush (Castilleja
applegatei); singleleaf pinyon/blackbrush/ Sandberg bluegrass (Poa secunda);
Utah juniper (J. osteosperma)/blackbrush/blue grama,
Utah juniper/blackbrush/Indian ricegrass (Achnatherum hymenoides); Utah juniper/blackbrush/mutton grass (Poa fendleriana)
southeastern Great Basin: Utah juniper/blackbrush/bottlebrush
squirreltail (Elymus elymoides)
In pinyon-juniper woodlands blackbrush is commonly
associated with Joshua tree, Our Lord's candle (Y. whipplei),
sagebrush, ephedra (Ephedra spp.), winterfat, and cactus (Opuntia
spp.) [55,56,100,105,126].
Relative blackbrush density varies dramatically by
plant community type; for example, 8,894 plants /ha were found in the blackbrush
scrub community type, while 647 plants/ha and 0 plants/ha were found on Joshua
tree woodland and Mojave mixed steppe sites, respectively [33]. In 1 canyon in California,
blackbrush cover ranged from 2.2% to 20.6%
of total plant cover [120]. In monospecific blackbrush shrublands, plant density and
species diversity are much lower than in adjacent shrublands [36,54]. On
blackbrush sites in Arizona, blackbrush contributed 82% to 95% of shrub cover
[45]. Though
few other shrubs occur in these stands, red brome (Bromus madritensis ssp.
rubens) and
cheatgrass (B. tectorum) may be the dominant understory species [16,17,18,23]. At sites in
southwestern Utah, blackbrush contributed 75%
of all plant cover, with red brome and cheatgrass accounting for 12% [23]. Big galleta (Pleuraphis rigida)
also contributes substantially to understory vegetation in blackbrush communities
[18]. The blackbrush overstory tends to preclude extensive understory
development [19,125]; however, herbaceous plants tend to occur in greatest
abundance on the periphery of blackbrush canopies, indicating the presence of
a more favorable microenvironment near the shrubs and a lack of any toxic effect
exerted by blackbrush [17,23].
Blackbrush also commonly occurs with the following
shrubs and grasses: fourwing saltbush (Atriplex canescens), desert
bitterbrush (Purshia glandulosa), shrub live oak (Quercus turbinella),
Cooper's heathgoldenrod (Ericameria cooperi), Fremont's dalea (Psorothamnus fremontii), white burrobush (Hymenoclea
salsola),
Anderson wolfberry (Lycium andersonii), broom snakeweed (Gutierrezia sarothrae),
desert globemallow (Sphaeralcea ambigua), spiny mendora (Menodora
spinescens), bladdersage (Salazaria mexicana), blue yucca,
banana yucca (Y. baccata), galleta (Pleuraphis jamesii), threeawn
(Aristida spp.), arid needlegrass (Achnatherum arida), desert needlegrass
(A.
speciosum), needle-and-thread grass (Hesperostipa comata), black grama (Bouteloua eriopoda), blue grama
(B. gracilis),
western wheatgrass (Pascopyrum smithii), and California buckwheat (Eriogonum
fasiculatum) [1,5,13,16,62,65,69,71,89,95,96,107,118,119,124].
Publications describing blackbrush-dominated plant communities are:
AZ [51,70,87,102,126]
CA [39,73,114,126]
NV [30,54,58,89,96,107,108,124,126]
UT [16,124]
Removal of spinescent material from blackbrush plants
stimulates sprouting from basal and axillary buds; therefore, plants that are
heavily browsed by livestock produce large quantities of new, more accessible
growth [79,80,85,112]. Browsing improves nutritional quality of blackbrush twigs
by increasing current-season growth; however, browsing may decrease palatability
due to high tannin levels in current-season growth [86]. Nutritional value
varies in response to browsing treatments: low protein and high tannin content
persists, though current-season growth generally has increased protein [80].
Heavy browsing followed by 1 to 2 years of rest allows blackbrush to accumulate
twigs that are more palatable because they are lower in tannins due to lower
proportions of current-season growth [80,84,85,86]. Domestic goats can be used
to remove spinescent growth and increase production of current-season growth to
improve forage for cattle; however, the low crude protein levels may cause a
reduction in livestock weight [83,112]. Livestock browsing on blackbrush should
be supplemented with protein to improve rumen function and minimize weight loss
[80,84,85]. With intensive management, stocking intensities of 1.8 AUM/ha can be
maintained [80].
Blackbrush can produce substantially larger amounts
of current growth with somewhat greater palatability and nutritional value
through the use of mechanical or browsing treatments [112].
Prescribed burning can lead to replacement by other shrubs, diversifying plant
communities and increasing the winter forage base, which may increase livestock
carrying capacity [8,112]. Because blackbrush exhibits
strong apical dominance that suppresses annual twig growth, removal of terminal
buds during the dormant winter season stimulates lateral twig growth during the
spring [81,82]. Brush beating damages
plants and stimulates growth of new shoots, improving forage quality
[17]. The results of a simulated brush beating in different plant communities 1 year after treatment are presented below.
Blackbrush plants in the blackbrush association responded better to the brush
beating treatments than blackbrush plants in either the Joshua tree/blackbrush
or Utah juniper/blackbrush associations. The number of blackbrush plants (out of 30
at each location) is presented according to the response to brush-beating
treatment and the plant community in which the blackbrush occurred [16]:
Total
Efforts to manipulate blackbrush rangelands
to increase forage production have produced unanticipated results [6].
Blackbrush stands might be manipulated for improvement of forage quality and
quantity without destroying the original vegetation; however, the manipulation
may open the
plant community to the invasion of other, perhaps less desirable, species [17].
Twig nutrition varies by location on the plant; twigs
from basal branches, located within the canopy, are higher in crude protein and
in-vitro digestible matter than those on older, terminal branches, located at
the outer edges of the canopy [79,82,86]. Blackbrush nutrition has been evaluated according to plant part
[16,17,118]: the following table compares
the nutritional content of leaves and stems [16,17]:
Blackbrush leaves and stems exceed the minimum
carotene required for gestating and lactating domestic animals but are deficient in phosphorus for domestic cattle and sheep during gestation and
lactation [16,17]. Ether extract is comparable to that of big sagebrush and black
sagebrush (Artemisia nova) during the winter [16,17].
Blackbrush flowers only in spring, probably the result of photoperiodism [1]. Flowering is induced by moderate to heavy winter precipitation [9,56]. Increases in winter precipitation and resulting soil moisture contribute to an abundance of flowers and seeds [16]. Flower buds begin to develop at the tips of terminal or lateral branches 2 weeks after the shoot growth begins and are fully open after 5 weeks [1,16,17]. By 6 weeks, 80 to 100% of the flowers are open, and no further twig elongation occurs once the flowers are fully developed [16,17]. Blackbrush at high elevations has a shorter flowering period than blackbrush at lower elevations, and flowering on individual plants is not synchronous, occurring over a 1- to 3-week period [56]. Fruits begin to develop in late April and early May [1,16,17].
After growth ceases in June, older outermost leaves yellow and dry out. Abscission occurs in July and August, causing a large buildup of organic matter [1,2,16,17]. Blackbrush may lose most of its leaves during summer dormancy, but retains enough leaves at the ends of branches to be considered an evergreen species [1,2].
Blackbrush phenophases vary according to location within its range. The following table lists the mean initial date of each phenophase along an elevation gradient from 4,900 to 5,900 feet (1,500-1,800 m) in southern Nevada. Standard errors and significant ( p?0.05) differences are denoted by a and b, respectively [56].
Phenophase Lower ecotone Pure stand Upper ecotone shoot budding 28 Feb + 4a 5 March + 4ab 10 March + 4b leafing 8 March + 4a 14 March + 4ab 19 March + 3b flower budding 28 April + 4a 28 April + 5ab 5 May + 4b flowering 1 May + 5a 6 May + 5ab 13 May + 4b fruiting 17 May + 5a 23 May + 4ab 29 May + 4bBlackbrush generally has a low germination rate [9,121], but with heavy, early spring rains, blackbrush seeds germinate in relatively large numbers. These may be the only conditions under which substantial germination occurs, suggesting that "pulse" climatic events are needed for establishment [9,10,121]. Soil moisture is required before seeds will break dormancy; watering at 2-week intervals was found to increase germination more than watering at 1- or 3-week intervals [53]. Germination of blackbrush seeds requires cold stratification without light [16,17,53]. Germination has been found to increase from 53% with no treatment to 83% after 7 weeks of cold stratification at 39 degrees Fahrenheit (4 oC) [16,17,29,53]. Seeds have also been found to respond to a moist storage at 41 degrees Fahrenheit (5 oC) and germinate at that temperature [118].
Germination patterns vary as a function of climate and elevation. Seeds collected from low-elevation sites were less dormant than seeds from high elevation sites in southern Utah and Nevada; the seeds from the 3,930-foot (1200 m) sites required a shorter chilling period to increase germination response than those from the 5,085-foot (1550 m) sites [53]. This relationship between dormancy status and site elevation may indicate that blackbrush has evolved ecotypes [53,75]. Dreeson and Harrington [29] found that substantial age and source differences are apparent in regard to population germination and/or stratification requirements. The sensitivity of seeds to salinity may be a limiting factor governing the distribution of blackbrush [17,118].
Blackbrush has a slow growth rate [57,121] that may be the result of shallow soils and an often-present caliche layer, which impede root growth and soil moisture [57].Blackbrush displays no natural vegetative reproduction [64], but regeneration can be achieved with asexual propagation from artificial cuttings. One-year growth has been found to produce a higher percentage of rooted cuttings, more roots, and longer roots than older growth [40].
Coleogyne ramosissima or blackbrush, is a low lying, dark grayish-green, aromatic,[2] spiny, perennial, soft wooded[2] shrub, native to the deserts of the southwestern United States.[3][4] It is called blackbrush because the gray branches darken when wet by rains.[3][4] It is in the rose family (Rosaceae),[3][4] and is the only species in the monotypic genus Coleogyne.
It has dense, intricate branches ("ramosissima" means "many branched").[4] Its dense branches form spiny tips.[4] This plant forms vast pure stands across the desert floor and on scrubby slopes, giving the landscape a uniform dark-gray color.[3] Vegetative types in which it dominates or is a codominate are called blackbrush scrub.[3][4]
It drops most of its leaves and becomes dormant in conditions of severe dryness (drought-deciduous), but some leaves are usually retained at the end of the branches.[3] The thickly branched plant forms thickets which may spread across the ground in clumps or grow erect to approach six feet in height in the Mojave Desert,[3] and 4 feet in the Canyonlands desert region.[4]
Flowers have 4 yellowish sepals, many yellow stamens, and may have 4 or no petals.[4] It is atypical of members of the rose family in that the flowers have no petals, have four rather than five sepals, and the leaves are opposite (occur in pairs on the twig), rather than alternate (occurring one at a time going up the twig.[3][5] The sepals may persist on the plant.[4] It flowers between April and July.
The leaves are inversely lanceolate, up to 3/8" long, have a small point at the tip, and are arranged in opposite pairs along the stem,[4] which is uncommon in members of the rose family.[5]
It forms vast communities in the Canyonlands region,[4] and in the Mojave Desert.[3]
Flowering is triggered by a heavy spring rain in this desert-adapted species. The leathery flowers grow at the ends of small stems. They are encased in thick, fuzzy sepals which are yellow inside and reddish or orange on the outer surface. There are no petals, but the sepals remain after the flower opens, surrounding the patch of whiskery stamens and the central pistil. The fruit is an achene a few millimeters long. The plant reproduces from seed, but very rarely. The seeds do not disperse well and seedlings do not survive in large numbers. A narrow range of temperature and moisture is required for the reproduction of this species, so it is sporadic, but the plants are hardy and long-lived.
Coleogyne ramosissima produces stenophyllanin A, an ellagitannin.[6]
Coleogyne ramosissima or blackbrush, is a low lying, dark grayish-green, aromatic, spiny, perennial, soft wooded shrub, native to the deserts of the southwestern United States. It is called blackbrush because the gray branches darken when wet by rains. It is in the rose family (Rosaceae), and is the only species in the monotypic genus Coleogyne.
