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Uzi Plitmann

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systematics and evolution particularly of: domesticated plant, leguminosae...reproductive biology of plants, e.g. breeding systems.population bio-ecology of parasitic plants.biogeography of Middle-eastern species.

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Natural History Museum, London

Gwen Robbins Schug

University of North Carolina at Greensboro

Universidade de São Paulo

girolamo fiorentino

University of Salento

Jesper Hoffmeyer

University of Copenhagen

Unisinos

Griffith University

Richard Cloutier

Université du Québec à Rimouski

Stephen McLoughlin

Swedish Museum of Natural History

Arizona State University

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Papers by Uzi Plitmann

Ha-magdir le-tsimhe bar be-Eretṡ Yiʹsraʾel

Factors affecting the extinction or survival of parasitic higher plants

Holoparasites in primary habitats mostly have a limited distribution. They grow in some sort of e... more Holoparasites in primary habitats mostly have a limited distribution. They grow in some sort of equilibrium with the flora of their natural ecosystem, due to particular adaptive habits like limited dispersal and restrained infestability. Their survival depends on a combination of biological and demographic characters of their hosts, their own ecological demands, and environmental conditions that affect their development. Significant change of any of these factors may result in severe reduction of the parasite's population and eventually in its elimination. Such changes can be caused by human interferences, by catastrophes, or by natural succession; they may affect the parasite direCtly, or its host's population, or the whole vegetation. The higher the specificity of the parasite, the higher are the chances of its going extinct. Parasites in secondary habitats, many of which have become cosmopolitan in distribution, are less prone to extinction than those in primary habitats, owing to their weed-like adaptations; only if hostspecific they may become rare or extinct when culture of their particular host crop is abandoned. Parasitic higher plants in both habitat types do not endanger the existence of their host species. Examples from the Cuscutaceae are briefly discussed. Two major questions arise when one deals with the diversity of parasitic higher plants within the generaI context of endangered species: (1) Are there threatened species among these plants? (2) Do they pose a threat upon the existence of their host species? There are about 3300 species of parasitic higher plants (i.e. 1.1-1.3 % of the seed plants), more than four fifths of which are semiparasites (mainly stem-parasitic Loranthaceae and root-parasitic Santalaceae and Scrophulariaceae) and less than one fifth are holoparasites (mainly root-parasitic Rajjlesiaceae and stem-parasitic Cuscutaceae). Most of the species, over twenty two hundred, are found in the tropical and subtropical regions of the world (

Alternative modes in dispersal strategies, with an emphasis on herbaceous plants of the Middle East

Proceedings, 1986

Hypotheses concerning diaspore behaviour are presented. It is suggested that in many plants, disp... more Hypotheses concerning diaspore behaviour are presented. It is suggested that in many plants, dispersal strategy involves alternative agents (2 or more vectors) and combination of distances. The hypotheses are substantiated by data compiled from observations of dispersal modes and mechanisms in herbaceous plant species of the Middle East. Two special modes, heterocarpy and amphicarpy, represent complex strategies with different propagules on the same individual. Amphicarpy resembles cryptophytic life-form in many respects. In several other cases the same propagule can be dispersed for various distances by a single vector or through alternative modes. Combination of long-range, short-range, and in situ dispersal is described for many species; Compositae of Turkey serve as a study case of the possible abundance of this strategy. Several combinations of different vectors that can distribute the same diaspores, alternately or successively, are recorded. It seems that the combination of wind and temporary water currents is quite common in our region. Cruciferae of Israel serve as a study case of the possible abundance of this strategy and its various combinations. It is concluded that dispersal strategies with alternate modes are typical of many herbaceous species and probably adopted by most angiosperms. The one-to-one conservative relationships between adaptation and mode, mechanism and agent, are rather misleading. An adaptation or a syndrome should not be rigidly defined as they may function in more than one way. Often, the alternate mode can be more effective than the mode attributed to that particular syndrome. By such strategy a plant can better guarantee its distribution in space.

Isozyme polymorphism in species of the genus Vicia (Leguminosae)

The Japanese Journal of Genetics, 1980

Thirty nine strains of 24 Vicia species representing the main sections of the genus, have been an... more Thirty nine strains of 24 Vicia species representing the main sections of the genus, have been analyzed for their isozyme patterns by disc electrophoresis of leaf and cotyledon extracts. The enzyme systems studied were amylase, esterase, glutamate oxaloacetic transaminase (GOT), indo-phenol oxidase (IPO). Comparing the zymograms obtained, one can arrive at the following conclusions: There are many bands common to species, series of sections and, in contrast, there are some bands differentiating between certain taxonomic categories. Such characterizing bands and patterns do not feature any clear general phylogenetic trend or systematic correlation. The enzymatic similarity does not necessarily correspond with the taxonomic relationships. GOT show lesser polymorphism, compared with amylase and esterase. The latter systems might be helpful in identifying species or strains. Species which are polymorphic in many other characters reveal also enzymatic polymorphism. Other possible correlations are briefly discussed, with a special note on the evolutionary implications of such a study in Vicia.

Pollen‐Pistil Relationships in the Polemoniaceae

Evolution, Sep 1, 1983

Dispersal strategies in the "Apiaceae": the temporal factor and its rolo in dissemination

Lagascalia, 1997

Agamospermy is much more common than conceived: A hypothesis

Israel Journal of Plant Sciences, 2002

ABSTRACT

Holocentric chromosome behaviour inCuscuta (Cuscutaceae)

Plant Systematics and Evolution, 1994

The present study demonstrates thatCuscuta babylonicaChoisy has holocentric chromosomes. Evidence... more The present study demonstrates thatCuscuta babylonicaChoisy has holocentric chromosomes. Evidence for this phenomenon comes from three different observations. (1) Mitosis: During metaphase and anaphase the sister-chromatids are situated parallel to the equatorial plane with no sign of localized kinetochore activity. (2) Inverted meiosis in microsporocytes. (3) X-rayed microsporocytes, in which the numerous chromosome fragments do not show any lagging or

Bimodal karyotype inCynomorium coccineumL. and its systematic implications

Botanical Journal of the Linnean Society, Mar 1, 1996

of a himodal karyotype in (i>mn/uriioni rorn'neurn (2n = 28) is used to support its srparation fr... more

Cytological Studies in Lopezieae (Onagraceae)

Botanical Gazette, Sep 1, 1975

... Type: Mexico, Guerrero, Mina, Yesceros-Cruz Pacifica, rocky slope in oak forest, 2,550 m, Nov... more

Pollen-Pistil Relationships in the Polemoniceae

Evolution, Sep 1, 1983

ABSTRACT

Cytogeographical distribution of the Old World «Lupinus»

Webbia, 1984

ABSTRACT

Distribution of Dimorphic Flowers as Related to Other Elements of the Reproductive Strategy

Plant Species Biology, Apr 1, 1995

Based on their functional role in reproduction, flower dimorphisms, whether structural or develop... more Based on their functional role in reproduction, flower dimorphisms, whether structural or developmental, can be categorized as (1) pollination‐related, (2) breeding‐related, and (3) dispersal‐related. Accordingly, flower dimorphism in Angiosperms is much more common than conceived before. For example, cleistogamy, considered a part of a multiple strategy in the breeding category, is found in over 200 species, 78% of which are herbaceous. It has haphazard systematic distribution and evolved in both zygomorphic (many Dicotyledones) and actinomorphic (many Monocots) flowers. The reproductive effort invested in the cleistogamous flowers proved to be by far smaller than in the chasmogamous ones. Thus cleistogamy has convergently evolved as an economical alternative mode of inbreeding in adverse conditions. Besides cleistogamy and its heteromorphic products, flower dimorphisms in general could be related to fruit dimorphism (heterocarpy) in some systematic groups. In the Tubuliflorae (Asteraceae) and the Apiaceae of Israel, heterocarpy is significantly more common among taxa with flower dimorphism. Flower and fruit dimorphisms represent a specialized or multiple reproductive strategy, with division of labour or alternative functions, in order to guarantee seed formation and dispersal even under stress.

Chromosome divergence in the genus<i>Cuscuta</i>and its systematic implications

Caryologia, 1995

-Cuscuta L. plants are holoparasites with high chromosome divergence. Species representing the th... more -Cuscuta L. plants are holoparasites with high chromosome divergence. Species representing the three subgenera of the genus were checked for their chromosome number, length and behaviour. Chromosome numbers range between 2n = 8 and 2n = 60, and their size, although roughly uniform within species, varies between 1-231J.m. On the whole, size or number of Cuscuta chromosomes cannot be used as diagnostic criteria, except for very few species with unique numbers or sizes. Some associations between certain systematic entities and chromosome characters can be inferred. Species of the Old World of subgenus Cuscuta Engelm. are characterized by inverted meiosis and apparently by holocentric chromosomes, whereas species of the two other subgenera, subgenus Monog;yna Engelm. and subgenus Grammica Yuncker, undergo the regular process of meiosis and have monocentric chromosomes. The presence of holocentric chromosomes does not seem to be associated with their number.

The Systematics of Lopezieae (Onagraceae)

Annals of the Missouri Botanical Garden, 1973

floral biology because of their flowers, which are both intricate and reduced in the number of th... more floral biology because of their flowers, which are both intricate and reduced in the number of their parts. In his review of the group, Munz (1961: 73) pointed out that further studies would be necessary even to set reasonable generic limits in Lopezieae, much less specific ones. The present revision represents several years of study in the field, experimental greenhouse, and herbarium, and brings to bear rather extensive information from morphology, floral anatomy (Eyde & ">rgan, 1973), cytology (Plitmann, Raven & Tai, 1974), pollination biology (Raven, Breedlove, Gregory & Plitmann, 1974) on the classification of the group. As Eyde and Morgan (1973) have emphasized, this small group of 21 species is of unusual interest in its mixture of generalized and derivative floral features. Largely restricted to Mexico, with three species extending to Guatemala and one to El Salvador and one subspecies confined to El Salvador, Costa Rica, and Panama, Lopezia occupies a wide variety of habitats. Some species are regularly visited and pollinated by hummingbirds; other by flies, principally syrphids; and still others are autogamous. Also of interest is the range of chromosome numbers in the group, which includes not only n = 11, presumbably basic for the family as a 1 We are most grateful for the support provided through a series of grants from the U. S.

New Taxa and Recombinations in Lopezia (Onagraceae)

Annals of the Missouri Botanical Garden, 1972

Assessing functional reproductive traits from herbaria] material: the test case of pollen tubes in pistils of <i>Polemoniaceae</i>

Taxon, Feb 1, 1994

SummaryPlitmann, U.: Assessing functional reproductive traits from herbarial material: the test c... more SummaryPlitmann, U.: Assessing functional reproductive traits from herbarial material: the test case of pollen tubes in pistils of Polemoniaceae. –Taxon 43: 63‐69. 1994. – ISSN 0040‐0262.Herbarium material can be used for studying certain functional reproductive traits, such as the plant's breeding system. A method is proposed by which pollen tubes can be traced in the pistil even in old dry specimens. By applying this method to species of the Polemoniaceae, microgametophytes could be scored in stigmas and styles and their mean numbers related to the specific known or putative breeding systems. Mean numbers of pollen tubes showed high correlation with the pollen‐ovule ratios or the stigmatic pollen germination of the species involved. These numbers were significantly higher in predominant inbreeders than in predominant or facultative out‐breeders. The method is thus suited for obtaining accessory biosystematic information from herbarial material.

Unusual chromosome separation in meiosis of Cuscuta L

Genome, Aug 1, 1991

This study suggests that precocious division of centromeres and probably inverted meiosis (i.e., ... more This study suggests that precocious division of centromeres and probably inverted meiosis (i.e., the rare occasion in meiosis when the equatorial division precedes the reductional division) occur not only in Cuscuta babylonica Choisy but also in several other dodders, regardless of their chromosome number. It was found in four additional species, all of which belong to subgenus Cuscuta. At least two other species (of subgenus Grammica and subgenus Monogyna) undergo the usual process. Therefore, Cuscuta warrants closer study and may provide a better understanding of inverted meiosis as well as the regular process of meiosis.Key words: inverted meiosis, precocious division of centromere, Cuscuta spp.

Evolutionary History of the Old World Lupines

Taxon, May 1, 1981

SummaryAbout twelve species of Lupinus are centered in the Mediterranean and North African parts ... more SummaryAbout twelve species of Lupinus are centered in the Mediterranean and North African parts of the Old World. They show limited morphologocal polymorphism, but they are diverse in other ways. The group as a whole features three unique characteristics of evolutionary significance: (a) a special geographical distribution, disjunct from the main center in America, with allopatric rough‐seeded and partially sympatric smooth‐seeded species; (b) karyotype polymorphism, with at least seven different chromosome numbers, none of which has been encountered in the New World; (c) systematic disassociation, by which most species are taxonomically unrelated and genetically isolated.This cyto‐geographical complex pattern and systematic divergence are best understood on the assumption that a few lupines of various origins migrated by means of long‐range dispersal from their primary center in North America during the Neogene. The migrations were repeated quite haphazardly.Rough‐seeded migrules were established in NW Africa, while smooth‐seeded ones arrived at the Mediterranean, probably later on.During the Miocene lupine populations spread and diverged along the Mediterranean and in Africa north of the equator, succeeding the Tethyan flora.Their present eco‐geographical distribution is the outcome of both climatic and edaphic changes during the Quaternary, combined with the impact of human activities from the Pleistocene on. Whereas the evolution of Lupinus in the New World has been enhanced by processes such as ecological differentiation and intensive hybridization, that of the Old World lupines has been inhibited owing to rapidly increasing aridity and civilization. The main changes in the gene pool of wild populations could be caused by disruptive differentiation, i.e., occasional hybridization and subsequent intergradations with escaped or neglected, sporadically domesticated strains.

Chromosome polymorphism, hybridization and colonization in theVicia sativa group(Fabaceae)

Plant Systematics and Evolution, 1979

Ha-magdir le-tsimhe bar be-Eretṡ Yiʹsraʾel

Factors affecting the extinction or survival of parasitic higher plants

Holoparasites in primary habitats mostly have a limited distribution. They grow in some sort of e... more Holoparasites in primary habitats mostly have a limited distribution. They grow in some sort of equilibrium with the flora of their natural ecosystem, due to particular adaptive habits like limited dispersal and restrained infestability. Their survival depends on a combination of biological and demographic characters of their hosts, their own ecological demands, and environmental conditions that affect their development. Significant change of any of these factors may result in severe reduction of the parasite's population and eventually in its elimination. Such changes can be caused by human interferences, by catastrophes, or by natural succession; they may affect the parasite direCtly, or its host's population, or the whole vegetation. The higher the specificity of the parasite, the higher are the chances of its going extinct. Parasites in secondary habitats, many of which have become cosmopolitan in distribution, are less prone to extinction than those in primary habitats, owing to their weed-like adaptations; only if hostspecific they may become rare or extinct when culture of their particular host crop is abandoned. Parasitic higher plants in both habitat types do not endanger the existence of their host species. Examples from the Cuscutaceae are briefly discussed. Two major questions arise when one deals with the diversity of parasitic higher plants within the generaI context of endangered species: (1) Are there threatened species among these plants? (2) Do they pose a threat upon the existence of their host species? There are about 3300 species of parasitic higher plants (i.e. 1.1-1.3 % of the seed plants), more than four fifths of which are semiparasites (mainly stem-parasitic Loranthaceae and root-parasitic Santalaceae and Scrophulariaceae) and less than one fifth are holoparasites (mainly root-parasitic Rajjlesiaceae and stem-parasitic Cuscutaceae). Most of the species, over twenty two hundred, are found in the tropical and subtropical regions of the world (

Alternative modes in dispersal strategies, with an emphasis on herbaceous plants of the Middle East

Proceedings, 1986

Hypotheses concerning diaspore behaviour are presented. It is suggested that in many plants, disp... more Hypotheses concerning diaspore behaviour are presented. It is suggested that in many plants, dispersal strategy involves alternative agents (2 or more vectors) and combination of distances. The hypotheses are substantiated by data compiled from observations of dispersal modes and mechanisms in herbaceous plant species of the Middle East. Two special modes, heterocarpy and amphicarpy, represent complex strategies with different propagules on the same individual. Amphicarpy resembles cryptophytic life-form in many respects. In several other cases the same propagule can be dispersed for various distances by a single vector or through alternative modes. Combination of long-range, short-range, and in situ dispersal is described for many species; Compositae of Turkey serve as a study case of the possible abundance of this strategy. Several combinations of different vectors that can distribute the same diaspores, alternately or successively, are recorded. It seems that the combination of wind and temporary water currents is quite common in our region. Cruciferae of Israel serve as a study case of the possible abundance of this strategy and its various combinations. It is concluded that dispersal strategies with alternate modes are typical of many herbaceous species and probably adopted by most angiosperms. The one-to-one conservative relationships between adaptation and mode, mechanism and agent, are rather misleading. An adaptation or a syndrome should not be rigidly defined as they may function in more than one way. Often, the alternate mode can be more effective than the mode attributed to that particular syndrome. By such strategy a plant can better guarantee its distribution in space.

Isozyme polymorphism in species of the genus Vicia (Leguminosae)

The Japanese Journal of Genetics, 1980

Thirty nine strains of 24 Vicia species representing the main sections of the genus, have been an... more Thirty nine strains of 24 Vicia species representing the main sections of the genus, have been analyzed for their isozyme patterns by disc electrophoresis of leaf and cotyledon extracts. The enzyme systems studied were amylase, esterase, glutamate oxaloacetic transaminase (GOT), indo-phenol oxidase (IPO). Comparing the zymograms obtained, one can arrive at the following conclusions: There are many bands common to species, series of sections and, in contrast, there are some bands differentiating between certain taxonomic categories. Such characterizing bands and patterns do not feature any clear general phylogenetic trend or systematic correlation. The enzymatic similarity does not necessarily correspond with the taxonomic relationships. GOT show lesser polymorphism, compared with amylase and esterase. The latter systems might be helpful in identifying species or strains. Species which are polymorphic in many other characters reveal also enzymatic polymorphism. Other possible correlations are briefly discussed, with a special note on the evolutionary implications of such a study in Vicia.

Pollen‐Pistil Relationships in the Polemoniaceae

Evolution, Sep 1, 1983

Dispersal strategies in the "Apiaceae": the temporal factor and its rolo in dissemination

Lagascalia, 1997

Agamospermy is much more common than conceived: A hypothesis

Israel Journal of Plant Sciences, 2002

ABSTRACT

Holocentric chromosome behaviour inCuscuta (Cuscutaceae)

Plant Systematics and Evolution, 1994

The present study demonstrates thatCuscuta babylonicaChoisy has holocentric chromosomes. Evidence... more The present study demonstrates thatCuscuta babylonicaChoisy has holocentric chromosomes. Evidence for this phenomenon comes from three different observations. (1) Mitosis: During metaphase and anaphase the sister-chromatids are situated parallel to the equatorial plane with no sign of localized kinetochore activity. (2) Inverted meiosis in microsporocytes. (3) X-rayed microsporocytes, in which the numerous chromosome fragments do not show any lagging or

Bimodal karyotype inCynomorium coccineumL. and its systematic implications

Botanical Journal of the Linnean Society, Mar 1, 1996

of a himodal karyotype in (i>mn/uriioni rorn'neurn (2n = 28) is used to support its srparation fr... more

Cytological Studies in Lopezieae (Onagraceae)

Botanical Gazette, Sep 1, 1975

... Type: Mexico, Guerrero, Mina, Yesceros-Cruz Pacifica, rocky slope in oak forest, 2,550 m, Nov... more

Pollen-Pistil Relationships in the Polemoniceae

Evolution, Sep 1, 1983

ABSTRACT

Cytogeographical distribution of the Old World «Lupinus»

Webbia, 1984

ABSTRACT

Distribution of Dimorphic Flowers as Related to Other Elements of the Reproductive Strategy

Plant Species Biology, Apr 1, 1995

Based on their functional role in reproduction, flower dimorphisms, whether structural or develop... more Based on their functional role in reproduction, flower dimorphisms, whether structural or developmental, can be categorized as (1) pollination‐related, (2) breeding‐related, and (3) dispersal‐related. Accordingly, flower dimorphism in Angiosperms is much more common than conceived before. For example, cleistogamy, considered a part of a multiple strategy in the breeding category, is found in over 200 species, 78% of which are herbaceous. It has haphazard systematic distribution and evolved in both zygomorphic (many Dicotyledones) and actinomorphic (many Monocots) flowers. The reproductive effort invested in the cleistogamous flowers proved to be by far smaller than in the chasmogamous ones. Thus cleistogamy has convergently evolved as an economical alternative mode of inbreeding in adverse conditions. Besides cleistogamy and its heteromorphic products, flower dimorphisms in general could be related to fruit dimorphism (heterocarpy) in some systematic groups. In the Tubuliflorae (Asteraceae) and the Apiaceae of Israel, heterocarpy is significantly more common among taxa with flower dimorphism. Flower and fruit dimorphisms represent a specialized or multiple reproductive strategy, with division of labour or alternative functions, in order to guarantee seed formation and dispersal even under stress.

Chromosome divergence in the genus<i>Cuscuta</i>and its systematic implications

Caryologia, 1995

-Cuscuta L. plants are holoparasites with high chromosome divergence. Species representing the th... more -Cuscuta L. plants are holoparasites with high chromosome divergence. Species representing the three subgenera of the genus were checked for their chromosome number, length and behaviour. Chromosome numbers range between 2n = 8 and 2n = 60, and their size, although roughly uniform within species, varies between 1-231J.m. On the whole, size or number of Cuscuta chromosomes cannot be used as diagnostic criteria, except for very few species with unique numbers or sizes. Some associations between certain systematic entities and chromosome characters can be inferred. Species of the Old World of subgenus Cuscuta Engelm. are characterized by inverted meiosis and apparently by holocentric chromosomes, whereas species of the two other subgenera, subgenus Monog;yna Engelm. and subgenus Grammica Yuncker, undergo the regular process of meiosis and have monocentric chromosomes. The presence of holocentric chromosomes does not seem to be associated with their number.

The Systematics of Lopezieae (Onagraceae)

Annals of the Missouri Botanical Garden, 1973

floral biology because of their flowers, which are both intricate and reduced in the number of th... more floral biology because of their flowers, which are both intricate and reduced in the number of their parts. In his review of the group, Munz (1961: 73) pointed out that further studies would be necessary even to set reasonable generic limits in Lopezieae, much less specific ones. The present revision represents several years of study in the field, experimental greenhouse, and herbarium, and brings to bear rather extensive information from morphology, floral anatomy (Eyde & ">rgan, 1973), cytology (Plitmann, Raven & Tai, 1974), pollination biology (Raven, Breedlove, Gregory & Plitmann, 1974) on the classification of the group. As Eyde and Morgan (1973) have emphasized, this small group of 21 species is of unusual interest in its mixture of generalized and derivative floral features. Largely restricted to Mexico, with three species extending to Guatemala and one to El Salvador and one subspecies confined to El Salvador, Costa Rica, and Panama, Lopezia occupies a wide variety of habitats. Some species are regularly visited and pollinated by hummingbirds; other by flies, principally syrphids; and still others are autogamous. Also of interest is the range of chromosome numbers in the group, which includes not only n = 11, presumbably basic for the family as a 1 We are most grateful for the support provided through a series of grants from the U. S.

New Taxa and Recombinations in Lopezia (Onagraceae)

Annals of the Missouri Botanical Garden, 1972

Assessing functional reproductive traits from herbaria] material: the test case of pollen tubes in pistils of <i>Polemoniaceae</i>

Taxon, Feb 1, 1994

SummaryPlitmann, U.: Assessing functional reproductive traits from herbarial material: the test c... more SummaryPlitmann, U.: Assessing functional reproductive traits from herbarial material: the test case of pollen tubes in pistils of Polemoniaceae. –Taxon 43: 63‐69. 1994. – ISSN 0040‐0262.Herbarium material can be used for studying certain functional reproductive traits, such as the plant's breeding system. A method is proposed by which pollen tubes can be traced in the pistil even in old dry specimens. By applying this method to species of the Polemoniaceae, microgametophytes could be scored in stigmas and styles and their mean numbers related to the specific known or putative breeding systems. Mean numbers of pollen tubes showed high correlation with the pollen‐ovule ratios or the stigmatic pollen germination of the species involved. These numbers were significantly higher in predominant inbreeders than in predominant or facultative out‐breeders. The method is thus suited for obtaining accessory biosystematic information from herbarial material.

Unusual chromosome separation in meiosis of Cuscuta L

Genome, Aug 1, 1991

This study suggests that precocious division of centromeres and probably inverted meiosis (i.e., ... more This study suggests that precocious division of centromeres and probably inverted meiosis (i.e., the rare occasion in meiosis when the equatorial division precedes the reductional division) occur not only in Cuscuta babylonica Choisy but also in several other dodders, regardless of their chromosome number. It was found in four additional species, all of which belong to subgenus Cuscuta. At least two other species (of subgenus Grammica and subgenus Monogyna) undergo the usual process. Therefore, Cuscuta warrants closer study and may provide a better understanding of inverted meiosis as well as the regular process of meiosis.Key words: inverted meiosis, precocious division of centromere, Cuscuta spp.

Evolutionary History of the Old World Lupines

Taxon, May 1, 1981

SummaryAbout twelve species of Lupinus are centered in the Mediterranean and North African parts ... more SummaryAbout twelve species of Lupinus are centered in the Mediterranean and North African parts of the Old World. They show limited morphologocal polymorphism, but they are diverse in other ways. The group as a whole features three unique characteristics of evolutionary significance: (a) a special geographical distribution, disjunct from the main center in America, with allopatric rough‐seeded and partially sympatric smooth‐seeded species; (b) karyotype polymorphism, with at least seven different chromosome numbers, none of which has been encountered in the New World; (c) systematic disassociation, by which most species are taxonomically unrelated and genetically isolated.This cyto‐geographical complex pattern and systematic divergence are best understood on the assumption that a few lupines of various origins migrated by means of long‐range dispersal from their primary center in North America during the Neogene. The migrations were repeated quite haphazardly.Rough‐seeded migrules were established in NW Africa, while smooth‐seeded ones arrived at the Mediterranean, probably later on.During the Miocene lupine populations spread and diverged along the Mediterranean and in Africa north of the equator, succeeding the Tethyan flora.Their present eco‐geographical distribution is the outcome of both climatic and edaphic changes during the Quaternary, combined with the impact of human activities from the Pleistocene on. Whereas the evolution of Lupinus in the New World has been enhanced by processes such as ecological differentiation and intensive hybridization, that of the Old World lupines has been inhibited owing to rapidly increasing aridity and civilization. The main changes in the gene pool of wild populations could be caused by disruptive differentiation, i.e., occasional hybridization and subsequent intergradations with escaped or neglected, sporadically domesticated strains.

Chromosome polymorphism, hybridization and colonization in theVicia sativa group(Fabaceae)

Plant Systematics and Evolution, 1979