Table of Contents
McLaughlin, S.P. 1993. Development of Hesperaloe species (Agavaceae)
as new fiber crops. p. 435-442. In: J. Janick and J.E. Simon (eds.), New
crops. Wiley, New York.
Development of Hesperaloe Species (Agavaceae) as New Fiber Crops
Steven P. McLaughlin
- SCREENING STUDIES
- BOTANY OF HESPERALOE
- AGRONOMIC STUDIES
- Size-Biomass Relationships
- Biomass Production
- Water Requirements
- Fertilizer Requirements
- Monthly Growth Rates
- Other Hesperaloe Species
- Table 1
- Table 2
- Fig. 1
- Fig. 2
- Fig. 3
- Fig. 4
- Fig. 5
- Fig. 6
"Hard fibers" are the bundles of fiber cells obtained by decorticating the
leaves of abaca (Musa textilis Née), sisal (Agave sisalana
Perrine), henequen (A. fourcroydes Lem.), and other monocots. These
fiber bundles are used mostly in cordage products (rope, twine, canvas,
burlap), but can be pulped for use in specialty papers (Clark 1965; Corradini
1979; da Silva and Pereira 1985), which include such products as tissue papers,
filter papers, tea bags, currency papers, and security papers. The very long
and thin fiber cells of these plants produce papers that are strong yet
fine-textured. The crop plants that produce the hard fibers of commerce are
all frost-sensitive tropical species. The objective of my research program is
to develop domestic production of a cold-tolerant source of hard fibers for use
in specialty papers.
Abaca and sisal pulps command premium prices in the paper industry (Clark 1965;
Baker 1985). Tensile strength, tearing resistance, and bursting strength, are
largely determined by fiber morphology (Horn and Setterholm 1990). The fiber
cells of abaca and sisal are as long or longer yet much thinner than those of
softwoods. Abaca fibers may average 6.0 mm in length and 24 µm in width, for a
length-to-width ratio (L/W) of 250. Sisal fibers are closer to 3.0 mm in
length with a L/W of 150.
We examined several species of Agavaceae native to the southwestern United
States and northern Mexico to determine if any of these plants possessed fibers
similar to those of abaca and sisal (McLaughlin and Schuck in press). An
updated summary of our results is presented in Table 1. Native species of
Agave, Nolina, and Dasylirion have relatively short fiber
cells. Species of Yucca and Hesperaloe have much longer and
narrower cells. Those of Hesperaloe species are comparable to abaca in
their L/W. From this screen, we selected Hesperaloe for further study.
The genus Hesperaloe consists of three described and two or more as yet
undescribed species; all are native to northern Mexico. Hesperaloe is
probably most closely related to the larger genus Yucca (Smith and Smith
1970). Hesperaloe funifera (Koch) Trel. (Fig. 1A) is found at lower
elevations in the east-central part of the Chihuahuan Desert in Coahuilla and
Nuevo Leon. Its Spanish common name is samandoque or zamandoque. H.
parviflora Torr. is the most widespread species, occurring at higher
elevations in the northern Chihuahuan Desert of Texas, Chihuahua, and
Coahuilla. It is widely cultivated as an ornamental plant in the southwestern
United States where it is called "red yucca." H. nocturna Gentry (Fig. 1B) is a recently described species from the Sierra Madre Occidental area of
northeastern Sonora; it has no Spanish or English common name. There are two
recently discovered Hesperaloe forms that probably represent new
species, one from the southeastern Chihuahuan Desert of San Luis Potosi and the
other from southern Sonora.
Hesperaloe species are long-lived, evergreen, acaulescent plants. As in
all Agavaceae, the basic module of growth is the rosette, a cluster of leaves
produced from a single meristem. This meristem produces several leaves before
switching from vegetative to reproductive mode. Once the flower stalk is
produced, the rosette ceases to grow. In Hesperaloe (as in most
Yucca) lateral or secondary rosettes are produced from the crown after
the primary rosette becomes reproductive. Although an older Hesperaloe
plant has the appearance of a closely packed, often grass-like clump of leaves
with several flower stalks, the plant actually consists of a cluster of
separate but closely-spaced rosettes. The older flowering rosettes are found
at the center of the clump; younger vegetative rosettes are on the periphery of
The species of Hesperaloe differ in their leaf morphology. The leaves
of H. funifera (Fig. 1A) and the undescribed species from San Luis
Potosi are 1 to 2 m long, 3 to 6 cm wide toward the base, and stiffly erect.
Those of H. funifera are cresent-shaped in cross section while those of
the undescribed species are more strongly folded into a V-shape. Leaves of
H. parviflora are less rigid, arching away from the crown, shorter
(mostly <1 m), narrower (1 to 2 cm), and cresent-shaped in cross section.
Leaves of H. nocturna (Fig. 1B) and the undescribed species from
southern Sonora are long (1 to 2 m), very narrow (mostly <1.5 cm wide), and
hemispherical in cross section. Leaves of all species bear marginal fibers.
Older plants of H. funifera typically consist of 10 or fewer rosettes
while those of H. nocturna and H. parviflora often have many more
than 10 rosettes.
All Hesperaloe species produce relatively large flower stalks--those of
H. funifera may be 3 to 4 m tall. The flowers of H. parviflora
and the undescribed species from Sonora are pink to red; those of the other
species are white to green.
There are no published studies on the agronomy of Hesperaloe species.
Our initial trials therefore, concentrated on determining the potential biomass
production of Hesperaloe funifera. This species was selected because
its fibers are very long and thin and small amounts of seed were available from
landscape plants growing in Tucson. While seed of H. parviflora are
more readily available, its fibers are consistently shorter than those in H.
funifera (McLaughlin and Schuck in press).
In the following text, standing crops and yields will be reported as fresh
weights. Standing crop refers to the amount of biomass present at any
particular time; yield refers to the amount of biomass obtained when the stand
is harvested. Because whole, cut leaves do not readily lose moisture, it is
most convenient to measure biomass as fresh weights. In addition, it is likely
that leaves would be transported and pulped as fresh material. Dry matter and
dry fiber contents of fresh leaves are approximately 32.5 and 10%, respectively.
H. funifera would be grown as a perennial crop (Fig. 2). Several years
would be required from the time of stand establishment to first harvest.
Plants harvested near ground level can regrow by (1) elongation of cut leaves
(monocot leaves grow from a basal meristem), (2) production of new leaves from
cut rosettes, and (3) production of new rosettes. It seems likely, therefore
that cut plants will regrow to produce several subsequent harvests.
Replicated production plots for H. funifera were established at three
densities: 6,800, 13,500, and 27,000/ha. Plots measured 9.75 by 30.5 m with
two plots at each density level. The low-density plots consist of 8 rows of 25
plants; medium-density plots have 8 rows of 50 plants, and high-density plots
have 16 rows of 50 plants. Plant spacings within the plots are: low density,
1.22 m between and within rows; medium density, 1.22 m between rows by 0.61 m
within rows; and high density, 0.61 m between and within rows. Plots were
established from transplants (3- to 5-month old seedlings) in March 1988; they
receive irrigation and fertilization through a below-ground drip irrigation
system. Soil moisture was monitored with gypsum blocks.
The key problem in monitoring growth and yield in such a perennial crop is
developing nondestructive methods of biomass estimation. We have measured
standing crops each year by randomly sampling 5 plants per row. On each plant,
basal circumference and average length of the five longest leaves were
measured. Two of the five plants in each row were harvested for fresh-weight
determinations. The number of plants harvested from the production plots each
year varied between 4 and 8% of the stand, depending on the density. Sampling
was done February 1989 (stand age 11 months), November 1989 (20 months), and
November 1990 (32 months).
The data on basal circumferences (cm), leaf length (cm), and fresh weights (g)
have been used to develop size-biomass relationships. Scatter diagrams show
that there is not a particularly good fit between either basal circumference
(Fig. 3A) or leaf length (Fig. 3B). However, basal area (BA, in
cm2) can be calculated from basal circumference (BC) as: BA =
BC2/(4p). I then defined a new variable, SIZE2, as: SIZE2 =
(BA)(Leaf Length)/1000. SIZE2 is proportional to the volume of the plant; it
is linearly related to fresh weight (Fig. 3C). Plotted on log-log scale the
relationship is linear with a very high R2 (Fig. 3D). We used the
equation for the relationship shown in Fig. 3D to estimate fresh weights on a
large sample of plants in the Production Study in August 1991; we also have
used it to estimate fresh weights nondestructively in other studies. This
equation works well for plants with a single rosette; a different size-biomass
equation probably will have to be developed for plants regrowing with two or
The development of the standing crops of Hesperaloe funifera at three
densities is shown in Fig. 4. During the first growing season, accumulation of
aboveground biomass is very slow as plants establish a large crown and an
extensive root system. Growth in subsequent years is rapid. Estimated
standing crops (leaves only) at the end of the third growing season were 22.1
46.7, and 77.4 Mg fresh weight/ha for the low-, medium-, and high-density
Standing crop to date is nearly directly proportional to density. Individual
plant size is inversely proportional to density but the effect so far is small.
Average plant size in the high-density plots at the end of 1990 (year 3) was
2632 g/plant compared to 3535 g/plant in the low-density plots.
Half of each of the 6 plots in the production study were harvested in November
1990. Plants are vigorously regrowing from the 5- to 8-cm stubble left from
the harvest, as expected (Fig. 5). Regrowth is occurring both from the
harvested rosettes and from new lateral rosettes. The average number of
rosettes per plant in these harvested plots is now 2.39, 1.88, and 1.56 in the
low-, medium-, and high-density plots, respectively. Since the basic unit of
growth is the individual rosette, the effective densities of these plots have
increased to 16,000, 25,000, and 42,000/ha, respectively.
To get a first approximation of this potential crop's water requirement, we
examined biomass production as a function of the amount of water applied.
While we have tried to balance water applications to rates of soil moisture
depletion, our system for monitoring soil moisture is not sophisticated and
irrigation schedules are far from optimized. Nevertheless, Hesperaloe
appears to have a rather low water requirement for an arid-land crop (Table 2).
In the high density plots, a total of 38.5 Mg dry weight has been produced with
a total application of 238 cm of irrigation, equivalent to a water requirement
of 6.2 cm/Mg dry weight of leaves. In comparison, alfalfa grown in Final Co.,
Arizona, requires 11.6 cm/Mg dry weight and kenaf grown in Imperial Co.,
California, requires 13.0 cm/Mg dry weight.
Leaf nitrogen levels were measured on leaves from 6 plants at the end of the
1990 growing season. Average N content was 1.42% (dry-weight basis) and did
not vary with density level or leaf age. Harvest of 77 Mg fresh weight/ha from
the high-density treatment at the end of the third growing season represents a
withdrawal of 358 kg N/ha; additional N is removed in the flower stalks, flower
parts, capsules, and seeds. The high-density plots were fertilized with only
120 kg N/ha over the first three years. Plants clearly used considerable
residual N in our plots and it is likely that growth has been limited by low N
to some unknown degree in our study.
Phosphorus contents averaged 0.13% of leaf dry weights, corresponding to a
removal rate of 32 kg P/ha over the first three years in the high-density plots.
Hesperaloe produces a fairly large flower stalk. In the 43 randomly
selected plants that flowered in 1990, the flower stalk (excluding dehisced
flowers and dispersed capsules and seeds) constituted 27% of the aboveground
fresh weight. At the end of the 1990 growing season (after the third growing
season), percentage of plants in flower ranged from 31% in the low-density
plots to 18% in the high-density plots. At the end of August 1991 (in the
fourth growing season) percentage of plants in flower in the unharvested
portions of our production plots averaged 57% and did not vary among density
We have been monitoring growth rates in a population of 20 Hesperaloe
funifera plants on a monthly basis since February 1990. These plants are
approaching the end of their second growing season. Number of leaves increases
most rapidly between June and October; rates of leaf elongation are greatest
during the same period. Basal circumference, however, continues to increase
through December. Thus, our estimates for fresh weight, which are based on
basal area and leaf length, continue to rise through December of the first
year. Estimated fresh weight begins increasing rapidly by May of the second
growing season (Fig. 6), consistent with our findings from the production study.
Hesperaloe nocturna has been grown in a small observation plot
and several plants of this species have been harvested on a yearly basis.
Fibers of this species are nearly as long as those of H. funifera; if
H. nocturna can be harvested at yearly intervals rather than the
projected 2-year interval for H. funifera, the former species might be a
superior crop plant. In October 1989, sufficient seed of H. nocturna
was collected from the wild for establishing a series of production plots. We
transplanted replicated plots of this species at densities of 6,800, 10,000,
13,500, and 20,000/ha in October 1990. Initial growth appears to be good;
these plots will be monitored for biomass production as they mature.
It is difficult at this initial stage of research and development on
Hesperaloe funifera to evaluate this plant's potential as a new crop.
We estimate that stands of Hesperaloe will need to produce annual yields
of 30 to 45 Mg fresh weight/ha (ca. 10 to 15 Mg dry weight) to produce biomass
at $40 to $60/Mg fresh weight (N.G. Wright and S.P. McLaughlin unpublished
analyses). This would correspond to a feedstock cost of $400 to $600/Mg dry
fiber. Leaf standing crop at the end of the third year was approximately 78 Mg
fresh weight/ha in the high-density plots, corresponding to an annual
productivity of 26 Mg fresh weight/ha. First-year aboveground growth rates,
however, were low. We estimate that the standing crop at the end of the fourth
year will be between 120 and 140 Mg fresh weight/ha, corresponding to an annual
productivity of 30 to 35 Mg fresh weight/ha. The rate of regrowth during the
first year after harvest appears to be much higher than the initial growth rate
during the first year after stand establishment.
The literature on cultivated Agave species indicates the magnitude of
yields that might be possible from perennial rosette plants in the Agavaceae.
Agave species are more succulent than Hesperaloe species (12% dry
matter vs. 32.5% dry matter, respectively, in the leaves) so that direct
comparisons of fresh weights are not meaningful. Nobel (1988) reported the
following dry-weight standing crops for 7-year-old stands of cultivated
Agave species: A. sisalana, 70 Mg/ha; A. fourcroydes, 80
Mg/ha; and A. tequilana, 90 Mg/ha. These would correspond to annual
yields of 10 to 13 Mg dry weight/ha similar to the targets I have set for
Hesperaloe. Nobel (1991) reported annual yields of 38 to 42 Mg/ha in
special plantings of A. mapisaga and A. salmiana at
Tequexquinahuac, Mexico. These yields are comparable to the maximum yields
observed in experiment station plants of C3 and C4 crops.
Initial predictions that 4 years would be required to reach a first harvest and
that subsequent harvests might be made every three years thereafter were proved
wrong. Stands should reach a harvestable standing crop after three years and
the amount of regrowth may be enough that subsequent harvests could be obtained
every two years.
Hesperaloe funifera, like Agave, is a CAM (crassulacean acid
metabolism) plant (Damian Ravetta unpublished data). The photosynthetic
pathways of other Hesperaloe species have not yet been determined, but
it is of interest to note that in Yucca, Hesperaloe's closest
relative, there are both CAM and C, species (Kemp and Gardetto 1982). The very
low water requirement of H. funifera is consistent with CAM
photosynthesis (Nobel 1991). High water-use efficiency, and hence low water
requirement, is an important criterion for potential new crops for arid regions
There appears to be a trade-off between flower-stalk production and leaf
production in H. funifera, i.e., investment of photosynthetically-fixed
carbon into flower stalks may decrease the amount of leaf production.
Selection for plants with delayed flowering might result in greater leaf
production at the first harvest. However, all rosettes must eventually
terminate in a flower stalk. Delayed flowering will only result in improved
leaf yields if it is accompanied by formation of an increased number of leaf
primordia. Also, flowering is correlated with the production of lateral
rosettes and an increased number of rosettes probably will result in larger
subsequent harvests. Determining what controls the number of leaves produced
by a rosette and what triggers production of flower stalks and lateral rosettes
will be critical to improving yields in this species.
- Baker, D.M. 1985. Alternative uses for sisal fiber, p. 177-186. In: C. Cruz,
L. del Castillo, M. Robert, and R.N. Ondara (eds.). Biologia y aprovechamiento
integral del henequen y otros Agaves. Centro de Investigacion Cientifica de
Yucatan, A. C.
- Clark, T.F. 1965. Plant fibers in the paper industry. Econ. Bot.
- Corradini, F.T. 1979. Companhia de Celulose da Bahia, p. 70-74. In: L.E.
Hass (ed.). New pulps for the paper industry. Proceedings of the Symposium on
New Pulps for the Paper Industry. Brussels, Belgium. May 1979. Miller
Freeman Publ., Inc., San Francisco.
- da Silva, N.M. and A.D. Pereira. 1985. Experience of a
pioneer--sisal--simultaneous resource for pulp and energy, p. 63-69. In: A.J.
Seaquist and E.C. Cobb (compilers). Nonwood plant fiber pulping: progress
report no. 15. TAPPI Press, Atlanta.
- Horn, R.A. and V.C. Setterholm. 1990. Fiber morphology and new crops, p.
270-275. In: J. Janick and J.E. Simon (eds.). Advances in new crops. Timber
Press, Portland, OR.
- Kemp, P.R. and P.E. Gardetto. 1982. Photosynthetic pathway types of evergreen
rosette plants (Liliaceae) of the Chihuahuan Desert. Oecologia 55:149-156.
- McLaughlin, S.P. 1985. Economic prospects for new crops in the southwestern
United States. Econ. Bot. 39:473-481.
- McLaughlin, S.P. and S.M. Schuck. 1992. Fiber properties of several Agavaceae
from the Southwestern United States and Northern Mexico. Econ. Bot. (in
- Nobel, P.S. 1988. Environmental biology of agaves and cacti. Cambridge
University Press, Cambridge.
- Nobel, P.S. 1991. Achievable productivities of certain CAM plants: basis for
high values compared with C3 and C4 plants. New Phytol. 119: 183-205
- Smith, C.M. and G.A. Smith. 1970. An electrophoretic comparison of species of
Yucca and of Hesperaloe. Bot. Gaz. 131:201-205.
Table 1. Average fiber lengths, widths, and cell-wall thicknesses for
five genera of Agavaceae from the southwestern United States and northern
|Genus ||No. species |
|Fiber length |
|Fiber width |
|Agave ||7 ||1.14 ||27.0 ||5.4 ||16.3 ||42|
|Dasylirion ||2 ||0.89 ||16.9 ||6.4 ||4.1 ||53|
|Nolina ||3 ||0.94 ||19.1 ||4.9 ||9.2 ||49|
|Hesperaloe ||5 ||3.55 ||14.7 ||3.6 ||7.5 ||241|
|Yucca ||9 ||2.38 ||14.3 ||5.8 ||2.7 ||166|
Table 2. Water requirement and productivity of Hesperaloe
funifera in the high-density treatment (27,000/ha).
zThrough August, 1991.
|Year ||Water applied |
|Estimated aboveground |
(Mg dry weight/ha)
(cm/Mg dry weight)
|1988 ||42 ||0.5 ||---|
|1989 ||46 ||10.1 ||4.6|
|1990 ||74 ||14.6 ||5.1|
|1991z ||76 ||13.3 ||5.7|
|4-year total ||238 ||38.5 ||6.2|
||Fig. 1. Hesperaloe funifera in the Chihuahuan Desert of central
Coahuilla (Fig. 1A) and H. nocturna in desert-woodland transitional
vegetation in northeastern Sonora (Fig. IB).
Fig. 2. Projected stand dynamics for Hesperaloe funifera grown
as perennial crop. We originally estimated that the plant would require 4
years to reach a first harvest with subsequent harvests every 3 years
thereafter (solid line): it now appears that a harvestable stand can be
produced in 3 years with reharvests every 2 years thereafter (dashed line).
Fig. 3. Size-biomass relationships in Hesperaloe funifera:
scatter diagrams showing the relationships between fresh weight and leaf length
(Fig. 3A), basal circumference (Fig. 3B), and the product of leaf length and
basal circumference on a linear plot (Fig. 3C) and a log-log plot (Fig. 3D).
||Fig. 4. Growth in standing crops of Hesperaloe funifera at three
stand densities (6,800, 13,500, and 27,000/ha): March 1988 to August 1991.
Bars show ± 1 standard error (SE); for data points without error bars, SE
<1 Mg fresh weight.
||Fig. 5. High-density plot of Hesperaloe funifera immediately
after harvest in November 1990 (Fig. 5A) and in September 1991 (Fig. 5B),
showing the rapid regrowth of the harvested stand.
||Fig. 6. Estimated standing crops (Mg fresh weight/ha) and growth rates
(Mg fresh weight ha-1 month-1) at 4-week intervals in a
sample of 20 plants of Hesperaloe funifera.
Last update September 15, 1997