Abstract
Early taxonomic treatments of the Echinocereus enneacanthus complex recognize five species: E. enneacanthus, E. dubius, E. stramineus, E. merkeri, and E. conglomeratus. Benson later made a major revision of the group's taxonomy and relegated dubius, stramineus, and conglomeratus to varietal status under E. enneacanthus. Two taxa, enneacanthus and dubius, form intergrading populations in the lower canyons of the Rio Grande in Brewster County, Texas. Field observations in Mexico reveal that E. merkeri and E. conglomeratus are synonymous with enneacanthus and stramineus, respectively. Members of the E. enneacanthus complex are pollinated by small, solitary halictid and anthoporid bees. No taxon specificity of pollinators was discovered. Breeding system studies revealed that members of the complex are xenogamous. Reciprocal crosses between enneacanthus and dubius were presumed highly fertile (above 80% seed set), while crosses of enneacanthus x stramineus exhibited reduced fertility (50% to 80% seed set). A consistent floral flavonoid discontinuity was found between stramineus and enneacanthus-dubius. Isorhamnetin (3'-O-methyl quercetin)-3-O-diglycosides were present in enneacanthus-dubius and absent from stramineus. These facts, coupled with data from artificial hybridization experiments, comparative morphology, geographic distribution, and ecological studies, reveal that Echinocereus enneacanthus var. stramineus is in reality a separate species, Echinocereus stramineus. No basis was found for the maintenance of dubius as a species or as a variety of E. enneacanthus. Commonly known as pitayas or alicoche, the Echinocereus enneacanthus complex is widely distributed within the confines of the Chihuahuan Desert. Many populations extend northward into the lower valley, plains, and canyons of the Rio Grande. In addition, populations occur in the Edwards Plateau and Trans-Pecos regions of Texas. Pitayas possess morphologically similar characters. In general they are caespitose, either loose and decumbent in habit, or erect and clustering tightly, with stout and rather large stems, 1.5 to 10 dm long. Flowers of pitayas are large, phlox-purple, and diurnal (Moore 1967). The fruits, especially of E. enneacanthus Engelm. var. stramineus (Engelm.) L. Benson, are quite edible. They taste and smell similar to strawberries, hence in the United States they are called strawberry cacti. In 1848 Engelmann described Echinocereus enneacanthus Engelm. Subsequently, as new specimens arrived from the United States-Mexico Boundary Survey, he described E. stramineus and E. dubius that were believed to be close relatives of E. enneacanthus. Later, Engelmann (1849) relegated Echinocereus (including E. enneacanthus) to subgeneric status under genus Cereus. Rumpler (1886) restored Echinocereus to generic status. Schumann (1898), following Engelmann's species concept and Ruimpler's generic concept, listed the three taxa as separate species of
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Claims 12
Claim · model-written summary
Enneacanthus and dubius form intergrading populations in Texas.
- Taxon
- Echinocereus enneacanthus
Echinocereus enneacanthust0 - Outcome
- intergrading populationse0
- Setting
- Brewster County, Texase0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Two taxa, enneacanthus and dubius, form intergrading populations in the lower canyons of the Rio Grande in Brewster County, Texas.”
t0“Echinocereus enneacanthus”
Claim · model-written summary
Field observations found E. merkeri synonymous with enneacanthus.
Verbatim
e0“Field observations in Mexico reveal that E. merkeri and E. conglomeratus are synonymous with enneacanthus and stramineus, respectively.”
Claim · model-written summary
Field observations found E. conglomeratus synonymous with stramineus.
Verbatim
e0“Field observations in Mexico reveal that E. merkeri and E. conglomeratus are synonymous with enneacanthus and stramineus, respectively.”
Claim · model-written summary
Members are pollinated by small solitary bees, without taxon specificity.
- Taxon
- E. enneacanthusEchinocereus enneacanthuse0
- Interactor
- halictid and anthoporid beese0pollinator
- Outcome
- pollinated by small, solitary halictid and anthoporid beese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Members of the E. enneacanthus complex are pollinated by small, solitary halictid and anthoporid bees. No taxon specificity of pollinators was discovered.”
Claim · model-written summary
Members of the complex are xenogamous.
- Taxon
- Echinocereus enneacanthusEchinocereus enneacanthust0
- Outcome
- xenogamouse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Breeding system studies revealed that members of the complex are xenogamous.”
t0“Echinocereus enneacanthus”
Claim · model-written summary
Enneacanthus and dubius reciprocal crosses had above 80% seed set.
- Taxon
- enneacanthus
Enneacanthuse0 - Material
- dubiuse0
- Outcome
- seed sete0
- Direction
- highly fertilee0
- Value
- above 80% seed sete0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reciprocal crosses between enneacanthus and dubius were presumed highly fertile (above 80% seed set)”
Claim · model-written summary
Enneacanthus by stramineus crosses had reduced fertility with 50% to 80% seed set.
- Taxon
- enneacanthusEnneacanthuse0
- Material
- stramineuse0
- Outcome
- fertilitye0
- Direction
- reducede0
- Value
- 50% to 80% seed sete0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“crosses of enneacanthus x stramineus exhibited reduced fertility (50% to 80% seed set).”
Claim · model-written summary
Floral flavonoids showed a consistent discontinuity between groups.
Verbatim
e0“A consistent floral flavonoid discontinuity was found between stramineus and enneacanthus-dubius.”
Claim · model-written summary
Isorhamnetin diglycosides were present in enneacanthus-dubius.
Not reportedDirection
Verbatim
e0“Isorhamnetin (3'-O-methyl quercetin)-3-O-diglycosides were present in enneacanthus-dubius and absent from stramineus.”
Claim · model-written summary
Isorhamnetin diglycosides were absent from stramineus.
Not reportedDirection
Verbatim
e0“Isorhamnetin (3'-O-methyl quercetin)-3-O-diglycosides were present in enneacanthus-dubius and absent from stramineus.”
Claim · model-written summary
The authors recognize stramineus as a separate species.
- Taxon
- Echinocereus enneacanthus var. stramineusEchinocereus enneacanthuse0
- Outcome
- a separate species, Echinocereus stramineuse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Echinocereus enneacanthus var. stramineus is in reality a separate species, Echinocereus stramineus.”
Claim · model-written summary
The authors found no basis to maintain dubius as a species or variety.
Verbatim
e0“No basis was found for the maintenance of dubius as a species or as a variety of E. enneacanthus.”