Carr, Gerald D.

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My research interests focus on biosystematics, speciation, and adaptive radiation in plants. Most of my work has involved chromosome evolution in a group of closely related Pacific Coast and Hawaiian genera that include the well-known Haleakala silversword. However, I am also collaborating with a number of other researchers on such aspects as molecular evolution, physiological diversification, and phytochemistry of these taxa. Our goal has been to provide a comprehensive, multidisciplinary perspective on the spectacular adaptive radiation that characterizes the Hawaiian element of this group.


Dr. Gerry Carr, Emeritus Professor
Department of Botany
1975 PhD. Botany
Oregon State University


Recent Submissions

Now showing 1 - 8 of 8
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    The Later Publications of Harold St. John
    (University of Hawaii Press, 1994-04) Carr, Gerald D.
    This paper lists the bibliography after 1980 of Dr. Harold St. John professor emeritus of the University of Hawaii Botany Department, who died 12 December 1991.
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    A Reassessment of Dubautia (Asteraceae: Heliantheae - Madiinae) on Kaua'i
    (University of Hawai'i Press, 1999-04) Carr, Gerald D.
    Aggressive botanical exploration of Kaua'i has yielded nearly 200 collections and two new species of Dubautia since the last monograph of the genus was published about a dozen years ago. This paper presents an updated key to the 13 species of Dubautia found on Kaua'i, summarizes and discusses the importance and systematic impact of recent collection data, and provides new maps to reflect the current knowledge of species distributions.
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    A Remnant Greensword Population from Pu'u 'Alaea, Maui, with Characteristics of Argyroxiphium virescens (Asteraceae)
    (University of Hawaii Press, 1998-01) Carr, Gerald D. ; Medeiros, Arthur C.
    Two unusual greenswords occurring on Pu'u 'Alaea in 1989 reportedly possessed vegetative features characteristic of the presumed extirpated species Argyroxiphium virescens Hillebr. One of these Pu'u 'Alaea plants flowered in August 1989, allowing detailed comparisons with preserved specimens of A. virescens as well as other species and hybrids of Argyroxiphium native to East Maui. These comparisons suggest that the unusual Pu'u 'Alaea greenswords represent remnants of hybridization between the now presumably extinct A. virescens and the more common Haleaka silversword, A. sandwicense subsp. macrocephalum (A. Gray) Meyrat, that still occurs at and adjacent to this site. The estimated pollen fertility of 62% in the Pu'u 'Alaea plant is consistent with this interpretation. Recovery of a few embryos from fruits of the plant that flowered in 1989 and the possibility of tissue culture of the remaining living plant at Pu'u 'Alaea apparently represent the last opportunities to conserve any vestige of A. virescens.
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    Two New Species in the Hawaiian Endemic Genus Dubautia (Compositae)
    (University of Hawaii Press, 1979-07) Carr, Gerald D.
    Two species of the Hawaiian genus Dubautia (subgenus Railliardiaster) are described as new. Dubautia herbstobatae (n = 13) is from Ohikilolo Ridge in the Waianae Mountains of Oahu; D. waianapanapaensis (n = 13) is from the upper Hana rain forest on Haleakala, Maui.
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    Reproductive Biology and Uniform Culture of Portulaca in Hawaii
    (University of Hawaii Press, 1990-04) Kim, Insun ; Carr, Gerald D.
    Ten taxa of Portulaca that occur in Hawaii (P. lutea, P. molokiniensis, P. oleracea, P. pi/osa, P. sclerocarpa, P. villosa, two imperfectly known species, and two cultivars) were included in a study of reproductive biology and uniform cultivation. The response of plants under uniform conditions upholds the merger of the reputed Hawaiian endemic P. cyanosperma with P. pilosa. All Portulaca taxa in Hawaii are autogamous, and in most instances large numbers of seeds are set even when the flowers are totally undisturbed. Some taxa are facultatively cleistogamous, but even in chasmogamous forms the flowers are open for only about 3-9 hr. The cultivars were the only taxa observed to attract pollinators, but P. molokiniensis, which was not studied in nature, appears to have adaptations for biotic pollination. Most of the portulac as studied have capsular fruit that require about 13-17 days to mature, but in P. sclerocarpa the fruits are thick-walled and indehiscent and require about 28 days for maturation. The life cycle ranges from about 8 weeks in most cases to several months in P. molokiniensis. However, individuals of most taxa typically flower and fruit man y times during one growing season. Seeds were generally nondormant, but partial seed dormancy was encountered in P. molokiniensis.
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    Cytogenetics of Hibiscadelphus (Malvaceae): A Meiotic Analysis of Hybrids in Hawaii Volcanoes National Park
    (University of Hawaii Press, 1977-04) Carr, Gerald D. ; Baker, James K.
    The chromosome number of 2n = 20 11 reported here is the first determination for Hibiscadelphus giffardianus Rock and H. distans Bishop & Herbst. An earlier report of the same number for H. hualalaiensis Rock is substantiated. Cytogenetic analysis of H. x puakuahiwi Baker & Allen, a hybrid cross between H. giffardianus and H. hualalaiensis suggests that chromosome pairing and microsporogenesis are not affected in the first generation. However, although chromosome pairing is normal at diakinesis in the seven F2S analysed, subsequent stages of meiosis and microsporogenesis are severely disturbed and result in the formation of a high percentage of abnormal meiospores in some of the plants. Nevertheless, the apparent lack of hybrid breakdown in two of the F2 plants and the presence of probable F3S in one area suggest that gene flow between the two taxa is possible, and, therefore, must be taken into consideration if these two endangered species are to be maintained as distinct entities.
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    Additional Chromosome Numbers of Hawaiian Flowering Plants
    (University of Hawai'i Press, 1985-07) Carr, Gerald D.
    Chromosome numbers of 30 collections representing 29 species and 16 families of Hawaiian flowering plants are presented an d discussed. The chromosome numbers of 24 of these species have not previously been reported. Chromosome numbers are also documented for the first time in the genera Colubrina (n = 24), Isodendrion (n = 8), Notho cestrum (n = c. 24), Remya (n = 18), and Schiedea (n = 30).
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    A Morphometric Analysis and Taxonomic Appraisal of the Hawaiian Silversword Argyroxiphium sandwicense DC. (Asteraceae)
    (University of Hawai'i Press, 1983-07) Meyrat, Alain ; Carr, Gerald D. ; Smith, Clifford W.
    Morphometric techniques were used to examine the pattern of variation of45 characters between the Haleakala and Mauna Kea populations of Argyro xiphium sandwicense. Qualitative features were also evaluated. A framework for a priori comparisons between the two populations of A. sandwicense was provided by including two additional species in the study, that is, A . kauense and .A. virescens var. paludosa. The F tests of one-way analysis of variance indicate that the means of each of 18 characters differ significantly (P ~ 0.05) between the two populations of A. sandwicense. Based on the presence of quantitative differentiation and geographical isolation and the near absence of qualitative differentiation between the two populations, it is proposed to recognize them as two different subspecies: A. sandwicense ssp. macrocephalum (Haleakala) and A. sandwicense ssp. sandwicense (Mauna Kea). The stud y also indicates that A . virescens var. paludosa, A . kauense, and A . sandwicense are distinct from one another in several quantitative and qualitative characters. Taxonomically useful quantitative characters include inflorescence proportions, leaf proportions, number of ray florets per capitulum, and capitulum diameter. The subspecies of A . sandwicense can be recognized on the basis of inflorescence proportions. However, to separate all four taxa, based on quantitative characters, a combination of at least three of the foregoing features appear to be needed . A taxonomic key and descriptions for common taxa ofArgyro xiphium of the island of Hawai'i and of East Maui are presented.