Table of Contents
Weber, D.J., W.M. Hess, R.B. Bhat, and J. Huang. 1993.
Chrysothamnus: A rubber-producing semi-arid shrub. p. 355-357. In: J.
Janick and J.E. Simon (eds.), New crops. Wiley, New York.
Chrysothamnus: A Rubber-producing Semi-arid Shrub
D.J. Weber, W.M. Hess, R.B. Bhat, and J. Huang
- BOTANY AND HORTICULTURE
- LEAF TRICHOMES
- Fig. 1
Chrysothamnus, a multi-use desert shrub which can grown in a wide range
of environmental conditions, has potential uses for revegetation (Sankhla et
al. 1987), as a forage for wildlife and livestock (Bhat et al. 1989), for
production of natural rubber (Hall and Goodspeed 1919), for production of
hydrocarbons from its biomass (Buchannon et al. 1978), for resin for polymer
plastics (Thames 1988), as a landscape shrub (Weber et al. 1986), and as a
potential source of natural chemical compounds (Hegerhorst et al. 1987a,c).
Production of natural rubber can be obtained from Chrysothamnus grown on
semi-arid lands where cold temperatures would exclude guayule and it could
provide resin for polymer plastics and specific chemical compounds for the
The genera, Chrysothamnus (Asteraceae), is endemic to the western United
States with 5 sections, 16 species, and 41 subspecies (Anderson 1986). Plants
in this genera can grow from Mexico to Canada and from sea level to 3,000 m.
The species, Chrysothamnus nauseosus (Pallas) Britt. (rubber
rabbitbrush) is a vigorous pioneer plant in disturbed sites. Plants can reach
heights of 30 to 180 cm with a few reaching heights of 366 cm. Rubber
rabbitbrush has a high rate of photosynthesis and does not become light
saturated at full sun (Davis et al. 1985). The average dry weight biomass per
plant is 29 kg and the average number of plants per ha in a normal population
is 2,632 (McKell and Van Epps 1980). Chrysothamnus nauseosus blooms in
the fall and the flowers are born in heads that in turn are raised into cymes,
racemes, or panicles. The heads contain five yellow disc flowers and are
subtended by involucral bracts. Each flower contains a pappus of abundant
white slender capillary bristles. The plant is self-fertile and entirely
diploid, although polyploidy does occur in one species.
Chrysothamnus nauseosus is a prolific producer of easily harvestable
seeds. Seeds germinate on most soils including saline sites in a few days
under cool nights (5°C) and warm days (15°C) (Khan et al. 1987).
Propagation by cuttings is difficult though possible, and in vitro propagation
techniques have been developed (Upadhyaya et al. 1985). The plants grow well
under arid conditions but produce more biomass with increased moisture.
Chrysothamnus nauseosus can tolerate both low freezing and hot arid
A number of the species of Chrysothamnus particularly nauseosus
contain rubber up to 7% dry weight. The average molecular weight of the rubber
varies in the species, but some species contain rubber with an average
molecular weight of 585,000 (Weber and Fernandes 1991). Rubber content was
found to be highest under stress conditions (Hegerhorst et al. 1987b).
The resin content of Chrysothamnus may be as high as 35% in some species
(Bhat et al. 1989) and the resin has potential use as a plastic extender
(Thames 1988). The resin, located in the leaves and in the glandular
trichomes, contain a range of terpenoid compounds including monoterpenes and
pregnanes (Weber and Fernandes 1991). The resin chemicals can be extracted and
have potential as a source of natural terpenes and insect inhibitors. The
pregnanes are chemically related to animal hormones (Deepak et al. 1989).
Plants and seeds of species and subspecies of Chrysothamnus were
collected from the western United States from a range of environmental
conditions and planted in a uniform garden. Leaf samples were collected from
the uniform garden when the leaves were fully mature. The leaf samples were
fixed, dehydrated, gold coated, and then observed with a scanning electron
microscope. There were two major types of trichomes observed, filiform and
glandular. A total of six variants of the filiform or glandular trichomes
could be distinguished (Fig. 1). In some cases, two or three types of
trichomes were present on the same leaf. In other cases, only one type of
trichome was present. The ratio of filiform to glandular trichomes on a single
leaf ranged from 1 in C. nauseous ssp. iridis L.C. Anderson to
11.9 in C. nauseous ssp. salicifolius (Rydb.) Hall & Clem.
The density varied greatly on the leaves of the different species. The number
of total trichomes per mm2 ranged from 1 in C. nauseous ssp.
graveolens (Nutt.) Piper to 301 in C. nauseous ssp.
viridulus (Hall) Hall & Clements. The number of trichomes per
mm2 did not correlate with resin content, amount of precipitation,
or summer temperatures.
- Anderson, L.C. 1986. An overview of the genus Chrysothamnus
(Asteraceae). In: E.D. McArthur and B.L. Welch (eds.). Proc. symposium on the
biology of Artemisia and Chrysothamnus. USDA Report INT 200.
- Bhat, R.B., B.L. Welch, D.J. Weber, and E.D. McArthur. 1989. Winter nutritive
value of Chrysothamnus nauseous ssp. J. Range Manag. 43:177-179.
- Buchannon, R.A., I.M. Cull, F.H. Otey, and C.R. Russell. 1978. Hydrocarbon
and rubber producing crops. Econ. Bot. 32:131-145.
- Davis, T.D., N. Sankhla, W.R. Anderson, D.J. Weber, and B.N. Smith. 1985.
High rate of photosynthesis in the desert shrub Chrysothamnus nauseous
ssp. albicaulis. Great Basin Natur. 45:520-526.
- Deepak, D., A. Khare, and P.K. Maheshwari. 1989. Plant pregnanes.
- Hall, H.M. and T.H. Goodspeed. 1919. Rubber-plant survey of western North
America. Univ. Calif. Pub. Bot. 7:159-278.
- Hegerhorst, D.F., D.J. Weber, and E.D. McArthur. 1987a. Resin and rubber
content in Chrysothamnus. Southwestern Natur. 32:475-482.
- Hegerhorst, D.F., D.J. Weber, R.B. Bhat, T.D. Davis, S. Sanderson, and E.D.
McArthur. 1987b. Seasonal changes in rubber and resin in Chrysothamnus
nauseous ssp. hololeucus and ssp. turbinatus. Biomass
- Hegerhorst, D.F., R.B. Bhat, D.J. Weber, and E.D. McArthur. 1987c. Seasonal
changes of selected secondary plant products in Chrysothamnus nauseous
ssp. turbinatus. Great Basin Natur. 48:1-8.
- Khan, M.A, N. Sankhla, D.J. Weber, and E.D. McArthur. 1987. Seed germination
characteristics of Chrysothamnus nauseous ssp. viridulus
(Astereae, Asteraceae). Great Basin Natur. 47:220-226.
- McKell, C.M. and G. Van Epps. 1980. Biomass energy production from large
growing rangeland shrubs. Utah State Univ, Logan.
- Sankhla, N., T.D. Davis, D.J. Weber, and D. McArthur. 1987. Biology and
economic botany of Chrysothamnus (rabbitbrush): a potentially useful
shrub for arid regions. J. Econ. Tax. Bot. 10:481-496.
- Thames, S.F. 1988. Agriculture products-their value to the polymer industry.
Guayule Rubber Society, 8th Annual Conference, Mesa, AZ.
- Upadhyaya, A., N. Sankhla, T.D. Davis, and D.J. Weber. 1985. In vitro
propagation of a rubber-producing desert shrub, Chrysothamnus nauseous
ssp. albicaulis. HortScience 20:864-865.
- Weber, D.J., T.D. Davis, D. McArthur, and N. Sankhla. 1986. Chrysothamnus
nauseous (rabbitbrush) multi-use shrub of the desert. Desert Plants
- Weber, D.J. and G.W. Fernandes. 1991. Insect galls and chemical composition
of leaves of Chrysothamnus nauseous ssp. hololeucus in riparian
and dry sites. In: Proc. Symposium on riparian sites. USDA Report INT 200.
|Fig. 1. Leaf surfaces of Chrysothamnus showing trichome types.
(1) C. nauseosus ssp. consimilis (Greene) Hall & Clem.
showing filiform tubular (arrow) and glandular biseriate (double arrows) types
x225. (2) C. nauseosus ssp. viridulus (Hall) Hall & Clements
showing ribbon types x225. (3) C. nauseosus ssp. salicifolius
(Rydb.) Hall & Clem showing filiform ribbon (arrow), glandular uniseriate
(double arrows), and glandular biseriate (triple arrows) types x225. (4) C.
viscidiflorus ssp. lanceolatus (Nutt.) Hall & Clem showing
prickle types x225. (5, 6) C. viscidiflorus ssp. viscidiflorus
(Hook.) Nutt. showing prickle multicellular (arrow) and glandular (double
arrows) types. x90; x450.
Last update September 12, 1997