We examined the effect of leaf rolling on CO2 and water vapor exchange of two C4 prairie grasses with contrasting patterns of leaf rolling. Andropogon gerardii (big bluestem) is a drought-resistant species with predominantly hypostomatal leaves that fold (adaxial surface inward) in response to low leaf water potential, while leaves of Spartina pectinata (prairie cordgrass), a mesic species, are epistomatal and roll into spirals (also adaxial surface inward). Adaxial stomata of both species are closed in completely rolled or folded leaves; thus these leaf movements have a minor effect on total leaf conductance. Energy budget calculations indicate that leaf rolling reduces transpiration by 7%-13% in water-stressed plants by lowering leaf temperature and, therefore, leaf-to-air vapor pressure deficit. This reduction is small relative to the direct effect of stomatal closure on transpiration. However, small decreases in transpiration, leaf temperature, and incident irradiance associated with leaf rolling may decrease the potential for photoinhibition, prolong physiological activity, and increase survival during drought.
{"title":"Effect of Leaf Rolling on Gas Exchange and Leaf Temperature of Andropogon gerardii and Spartina pectinata","authors":"S. Heckathorn, E. DeLucia","doi":"10.1086/337888","DOIUrl":"https://doi.org/10.1086/337888","url":null,"abstract":"We examined the effect of leaf rolling on CO2 and water vapor exchange of two C4 prairie grasses with contrasting patterns of leaf rolling. Andropogon gerardii (big bluestem) is a drought-resistant species with predominantly hypostomatal leaves that fold (adaxial surface inward) in response to low leaf water potential, while leaves of Spartina pectinata (prairie cordgrass), a mesic species, are epistomatal and roll into spirals (also adaxial surface inward). Adaxial stomata of both species are closed in completely rolled or folded leaves; thus these leaf movements have a minor effect on total leaf conductance. Energy budget calculations indicate that leaf rolling reduces transpiration by 7%-13% in water-stressed plants by lowering leaf temperature and, therefore, leaf-to-air vapor pressure deficit. This reduction is small relative to the direct effect of stomatal closure on transpiration. However, small decreases in transpiration, leaf temperature, and incident irradiance associated with leaf rolling may decrease the potential for photoinhibition, prolong physiological activity, and increase survival during drought.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"263 - 268"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337888","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Hidalgo, G. García-Herdugo, J. González-Reyes, D. Morré, P. Navas
Ascorbate free radical increased the growth of Allium cepa roots by 20%. The nature of this stimulation was not related to cell proliferation, for neither cell cycle nor mitotic index was affected. However, an ascorbate free radical-mediated cell-size increase was observed in both meristematic and elongating cells. Further, both plasma membrane- and tonoplast-associated ATPases were increased by ascorbate free radical, as were uptake of oxygen, nitrate, and sugars. The increase in plasma-membrane ATPase was in proportion to cell enlargement, while the effect on tonoplast was disproportionately greater. The results show an activation of the elongation component of root growth by ascorbate free radical without affecting the production of new meristematic cells.
{"title":"Ascorbate Free Radical Stimulates Onion Root Growth by Increasing Cell Elongation","authors":"A. Hidalgo, G. García-Herdugo, J. González-Reyes, D. Morré, P. Navas","doi":"10.1086/337891","DOIUrl":"https://doi.org/10.1086/337891","url":null,"abstract":"Ascorbate free radical increased the growth of Allium cepa roots by 20%. The nature of this stimulation was not related to cell proliferation, for neither cell cycle nor mitotic index was affected. However, an ascorbate free radical-mediated cell-size increase was observed in both meristematic and elongating cells. Further, both plasma membrane- and tonoplast-associated ATPases were increased by ascorbate free radical, as were uptake of oxygen, nitrate, and sugars. The increase in plasma-membrane ATPase was in proportion to cell enlargement, while the effect on tonoplast was disproportionately greater. The results show an activation of the elongation component of root growth by ascorbate free radical without affecting the production of new meristematic cells.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"282 - 288"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337891","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Three anatomically preserved endocarps, each with one enclosed seed, are described from the Princeton chert (Middle Eocene) Allenby Formation of British Columbia, Canada. Fruits are ovoid, unicarpellate, single-seeded drupes. Endocarps are sclerotic, with one or two ridges on the dorsal side, and a distinct ventral suture that is partially open toward the fruit apex where an obturator is present. Cells along the ventral suture are oriented parallel to the surface of the suture and have thin secondary walls and dark contents. Seeds are anatropous, bitegmic, and ventrally attached to the carpel, with a ventral raphe and a dorsal vascular plexus. The outer integument in two seeds is composed of a single layer with alternating sclereids and thin-walled cells, while in the third seed only sclereids are present. The inner integument consists of a single layer of rectangular, thin-walled cells, but the inner integument becomes multilayered in the micropylar region and along the vascular plexus. These three endocarps with enclosed seeds have a very similar anatomy. Variation in number of cell layers, and cell size and shape in each zone is similar to that seen in extant Prunus species. However, only seven out of about 430 species of Prunus have been studied in detail. This lack of information in extant Prunus makes the recognition of species difficult at this time. The description of these rosaceous fruits shows that by the Middle Eocene several postulated "advanced" characters in Prunoideae were already present.
{"title":"Fruits and Seeds from the Princeton Chert (Middle Eocene) of British Columbia: Rosaceae (Prunoideae)","authors":"R. Stockey","doi":"10.1086/337899","DOIUrl":"https://doi.org/10.1086/337899","url":null,"abstract":"Three anatomically preserved endocarps, each with one enclosed seed, are described from the Princeton chert (Middle Eocene) Allenby Formation of British Columbia, Canada. Fruits are ovoid, unicarpellate, single-seeded drupes. Endocarps are sclerotic, with one or two ridges on the dorsal side, and a distinct ventral suture that is partially open toward the fruit apex where an obturator is present. Cells along the ventral suture are oriented parallel to the surface of the suture and have thin secondary walls and dark contents. Seeds are anatropous, bitegmic, and ventrally attached to the carpel, with a ventral raphe and a dorsal vascular plexus. The outer integument in two seeds is composed of a single layer with alternating sclereids and thin-walled cells, while in the third seed only sclereids are present. The inner integument consists of a single layer of rectangular, thin-walled cells, but the inner integument becomes multilayered in the micropylar region and along the vascular plexus. These three endocarps with enclosed seeds have a very similar anatomy. Variation in number of cell layers, and cell size and shape in each zone is similar to that seen in extant Prunus species. However, only seven out of about 430 species of Prunus have been studied in detail. This lack of information in extant Prunus makes the recognition of species difficult at this time. The description of these rosaceous fruits shows that by the Middle Eocene several postulated \"advanced\" characters in Prunoideae were already present.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"369 - 379"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337899","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Leaf net photosynthesis (Pn), conductance to water vapor, water potential, solar radiation penetration within the canopy, and biomass production of Sporobolus flexuosus plants in the northern Chihuahuan Desert were measured 4, 18, and 34 d following removal of one-half of all shoots. Regrowth in partially defoliated plants was limited because of a delay in any substantial precipitation until relatively late in the growing season and the mature stage of plant development at the time of defoliation. There were no differences in Pn between partially defoliated and control plants 4 d after defoliation but on days 18 and 34, Pn rates of defoliated plants were 35% higher than for leaves of similar age on control plants. However, significant differences between treatments did not occur until midday when incident solar radiation was greatest. Daily integrated solar radiation penetration within the canopy of defoliated and control plants averaged 66% and 32%, respectively, of the total irradiance received in the open. The simultaneous direct effects of defoliation and indirect effects of increased irradiance levels within the canopy of partially defoliated plants may have contributed concurrently to the compensatory photosynthesis. Compensatory photosynthesis evident in this study was not due to changes in conductance or improvements in plant water status. There were no differences between treatments in leaf conductance but, on all three sample days, leaf water potentials of partially defoliated plants were 20%-30% more negative than those of control plants. Results of this study indicate that compensatory photosynthesis may be a common response in defoliated range grasses despite the suboptimal environmental conditions common in the field.
{"title":"Compensatory Photosynthesis of Sporobolus flexuosus (Thurb.) Rydb. Following Simulated Herbivory in the Northern Chihuahuan Desert","authors":"R. Senock, W. Sisson, G. B. Donart","doi":"10.1086/337890","DOIUrl":"https://doi.org/10.1086/337890","url":null,"abstract":"Leaf net photosynthesis (Pn), conductance to water vapor, water potential, solar radiation penetration within the canopy, and biomass production of Sporobolus flexuosus plants in the northern Chihuahuan Desert were measured 4, 18, and 34 d following removal of one-half of all shoots. Regrowth in partially defoliated plants was limited because of a delay in any substantial precipitation until relatively late in the growing season and the mature stage of plant development at the time of defoliation. There were no differences in Pn between partially defoliated and control plants 4 d after defoliation but on days 18 and 34, Pn rates of defoliated plants were 35% higher than for leaves of similar age on control plants. However, significant differences between treatments did not occur until midday when incident solar radiation was greatest. Daily integrated solar radiation penetration within the canopy of defoliated and control plants averaged 66% and 32%, respectively, of the total irradiance received in the open. The simultaneous direct effects of defoliation and indirect effects of increased irradiance levels within the canopy of partially defoliated plants may have contributed concurrently to the compensatory photosynthesis. Compensatory photosynthesis evident in this study was not due to changes in conductance or improvements in plant water status. There were no differences between treatments in leaf conductance but, on all three sample days, leaf water potentials of partially defoliated plants were 20%-30% more negative than those of control plants. Results of this study indicate that compensatory photosynthesis may be a common response in defoliated range grasses despite the suboptimal environmental conditions common in the field.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"275 - 281"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Festuca arundinacea Schreb., commonly infected by a fungal endophyte of the genus Acremonium, may also contain a second, referred to as the Phialophora-like, endophyte. Hyphae of this fungus are intercellular in tissues of the host leaf blade, sheath, and culm, reaching their greatest numbers in outermost leaf sheaths. They also become intracellular in senescing host tissues. Vegetative hyphae have apparently homogeneous walls, heavy cytoplasmic electron opacity, and a high lipid content. Utilization of lipid reserves in the form of large globules in green sheaths and blades results in the formation of heavy electronopaque bodies; these occur in reduced amount in senescent blades. In senescent sheaths, lipid globules are occasionally associated with numerous mitochondria covered in a close layer of conspicuous ribosomes. During early winter, when hyphae are most common in host tissues, reproductive structures of the Phialophora-like endophyte are found on and in outermost-senescing blades. Conidiomata take the form of penicillate tufts of mucilage-secreting conidiophores whose ultimate branches (phialides) bear enteroblastic conidia. Phialide cytoplasm contains much endoplasmic reticulum as both rough fenestrated cisternae and smooth cisternae of a proliferating form, often associated with the plasmalemma and connected to the nuclear envelope. Mitochondria are numerous throughout the cells of the conidioma and are conspicuous due to a coating of ribosomes. Conidia are borne at the apex of an elongated neck and are encircled by an upstanding or reflexed collarette. After schizolytic secession, conidia enlarge and continue maturation with elongation and contortion of the nucleus and depletion of reserve material. A zone of parallel-lying short lengths of peg- or rod-like structures, from which heterochromatin is excluded, lies within the inner membrane of the nuclear envelope. Ultrastructural similarities between the Gliocladium- and Phialophora-like endophytes of grasses suggest that these two fungi may be congeneric.
{"title":"Ultrastructure of a Symptomless Fungal Endophyte of Festuca arundinacea","authors":"M. Philipson","doi":"10.1086/337893","DOIUrl":"https://doi.org/10.1086/337893","url":null,"abstract":"Festuca arundinacea Schreb., commonly infected by a fungal endophyte of the genus Acremonium, may also contain a second, referred to as the Phialophora-like, endophyte. Hyphae of this fungus are intercellular in tissues of the host leaf blade, sheath, and culm, reaching their greatest numbers in outermost leaf sheaths. They also become intracellular in senescing host tissues. Vegetative hyphae have apparently homogeneous walls, heavy cytoplasmic electron opacity, and a high lipid content. Utilization of lipid reserves in the form of large globules in green sheaths and blades results in the formation of heavy electronopaque bodies; these occur in reduced amount in senescent blades. In senescent sheaths, lipid globules are occasionally associated with numerous mitochondria covered in a close layer of conspicuous ribosomes. During early winter, when hyphae are most common in host tissues, reproductive structures of the Phialophora-like endophyte are found on and in outermost-senescing blades. Conidiomata take the form of penicillate tufts of mucilage-secreting conidiophores whose ultimate branches (phialides) bear enteroblastic conidia. Phialide cytoplasm contains much endoplasmic reticulum as both rough fenestrated cisternae and smooth cisternae of a proliferating form, often associated with the plasmalemma and connected to the nuclear envelope. Mitochondria are numerous throughout the cells of the conidioma and are conspicuous due to a coating of ribosomes. Conidia are borne at the apex of an elongated neck and are encircled by an upstanding or reflexed collarette. After schizolytic secession, conidia enlarge and continue maturation with elongation and contortion of the nucleus and depletion of reserve material. A zone of parallel-lying short lengths of peg- or rod-like structures, from which heterochromatin is excluded, lies within the inner membrane of the nuclear envelope. Ultrastructural similarities between the Gliocladium- and Phialophora-like endophytes of grasses suggest that these two fungi may be congeneric.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"296 - 303"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A high percentage of intact mitochondria was isolated from Aranda flower petals. The state 3 and state 4 respiration of mitochondria isolated from flowers at different stages of development were different. The ADP/O (equivalent to P/O) and respiratory control (RC) ratios also varied when different substrates were added. Highest state 3 and state 4 rates were observed when malate and succinate or malate, succinate, and NADH were the substrates. Mature flower mitochondria have high P/O and RC ratios. Bud mitochondria, in contrast, have low P/O and RC ratios but can oxidize NADPH faster. A high degree of cyanide resistance and rotenone insensitivity was observed in bud mitochondria. The relationship of these findings to the need for energy and metabolic intermediates for bud growth in early stages of flower development is discussed.
{"title":"Respiration of Orchid Flower Mitochondria","authors":"C. Hew, K. Yip","doi":"10.1086/337892","DOIUrl":"https://doi.org/10.1086/337892","url":null,"abstract":"A high percentage of intact mitochondria was isolated from Aranda flower petals. The state 3 and state 4 respiration of mitochondria isolated from flowers at different stages of development were different. The ADP/O (equivalent to P/O) and respiratory control (RC) ratios also varied when different substrates were added. Highest state 3 and state 4 rates were observed when malate and succinate or malate, succinate, and NADH were the substrates. Mature flower mitochondria have high P/O and RC ratios. Bud mitochondria, in contrast, have low P/O and RC ratios but can oxidize NADPH faster. A high degree of cyanide resistance and rotenone insensitivity was observed in bud mitochondria. The relationship of these findings to the need for energy and metabolic intermediates for bud growth in early stages of flower development is discussed.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"289 - 295"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study deals with dividing more or less vacuolated cells and provides information about cytokinesis and the spatial relation in the differentiation of the cell plate. Vacuoles may disturb the distribution of cell contents and bring about abnormal completion of cell division. The study is also concerned with cells in which the vacuole is extra large and that must complete cell division by reference to a phragmosome system.
{"title":"Distribution of Vacuoles and Some Other Organelles in Dividing Cells","authors":"K. Esau, R. Gill","doi":"10.1086/337901","DOIUrl":"https://doi.org/10.1086/337901","url":null,"abstract":"This study deals with dividing more or less vacuolated cells and provides information about cytokinesis and the spatial relation in the differentiation of the cell plate. Vacuoles may disturb the distribution of cell contents and bring about abnormal completion of cell division. The study is also concerned with cells in which the vacuole is extra large and that must complete cell division by reference to a phragmosome system.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"37 1","pages":"397 - 407"},"PeriodicalIF":0.0,"publicationDate":"1991-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chromosome counts for eight species of Carex section Ovales were determined (C. bebbii, C. crawfordii, C. integra, C. microptera, C. pachystachya, C. praticola, C. preslii, and C. subfusca). Combined with data from previous studies in the sect. Ovales, chromosome number variability is observed within individuals, populations, and species. Counts from 10 sib families of C. pachystachya indicate that structural rearrangements occur between generations. A total of 38 of the approximately 70 species of the section have been counted. Sixteen species have been counted more than once: seven of these show no chromosome number variation, and nine have aneuploid series of numbers. Two forms of chromosome change are identified in the section: structural rearrangements and aneuploidy. At present the data cannot be used to determine whether strict aneuploidy or agmatoploidy accounts for the aneuploid variation.
{"title":"Chromosome Counts of Carex Section Ovales","authors":"R. Whitkus","doi":"10.1086/337884","DOIUrl":"https://doi.org/10.1086/337884","url":null,"abstract":"Chromosome counts for eight species of Carex section Ovales were determined (C. bebbii, C. crawfordii, C. integra, C. microptera, C. pachystachya, C. praticola, C. preslii, and C. subfusca). Combined with data from previous studies in the sect. Ovales, chromosome number variability is observed within individuals, populations, and species. Counts from 10 sib families of C. pachystachya indicate that structural rearrangements occur between generations. A total of 38 of the approximately 70 species of the section have been counted. Sixteen species have been counted more than once: seven of these show no chromosome number variation, and nine have aneuploid series of numbers. Two forms of chromosome change are identified in the section: structural rearrangements and aneuploidy. At present the data cannot be used to determine whether strict aneuploidy or agmatoploidy accounts for the aneuploid variation.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"224 - 230"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Single node explants of conventional, afila, and tendril-less peas (Pisum sativum L.) were cultured on a nutrient medium containing 2-200 μM TIBA. In conventional and tendril-less shoots, TIBA caused the development of: (i) a simple leaf rather than a compound leaf; (ii) a terminal leaflet in place of a normal tendril; (iii) a paripinnate leaf instead of the normal imparipinnate leaf; (iv) a ring fasciation; and (v) congenital fusion of two lateral leaflets. Tendrils borne on afila leaves were swollen radially and deeply cloven in the presence of TIBA. Pea leaf determination is a gradual process. Conventional pea tendrils are competent to form leaflet laminae, but they do not normally receive optimum levels of the appropriate signal at an early, critical stage. Afila tendril primordia are not competent to develop into leaflets. Tendrilless leaf primordia receive and can respond to signals for leaflet development. They are determined earlier than conventional leaves.
{"title":"Modification of Pea Leaf Morphology by 2,3,5-Triiodobenzoic Acid","authors":"K. Gould, E. G. Cutter","doi":"10.1086/337872","DOIUrl":"https://doi.org/10.1086/337872","url":null,"abstract":"Single node explants of conventional, afila, and tendril-less peas (Pisum sativum L.) were cultured on a nutrient medium containing 2-200 μM TIBA. In conventional and tendril-less shoots, TIBA caused the development of: (i) a simple leaf rather than a compound leaf; (ii) a terminal leaflet in place of a normal tendril; (iii) a paripinnate leaf instead of the normal imparipinnate leaf; (iv) a ring fasciation; and (v) congenital fusion of two lateral leaflets. Tendrils borne on afila leaves were swollen radially and deeply cloven in the presence of TIBA. Pea leaf determination is a gradual process. Conventional pea tendrils are competent to form leaflet laminae, but they do not normally receive optimum levels of the appropriate signal at an early, critical stage. Afila tendril primordia are not competent to develop into leaflets. Tendrilless leaf primordia receive and can respond to signals for leaflet development. They are determined earlier than conventional leaves.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"32 1","pages":"133 - 138"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/337872","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The gynoecial micromorphologies of Monotropa uniflora and M. hypopitys are compared to characterize the gynoecial pathway for pollen tube growth. The receptive surface of the concave stigma is restricted to a papillate rim coated with an exudate. An internal transmitting tissue in the stigma joins the papillae with an external transmitting tissue system formed by the lining of the fluted stylar canal that may limit pollen tube growth to specific ovule-bearing placentae. Consequently, pollen tube growth is facilitated in the vicinity of the ovular micropyles.
{"title":"Gynoecial Pathway for Pollen Tube Growth in the Genus Monotropa","authors":"A. Olson","doi":"10.1086/337875","DOIUrl":"https://doi.org/10.1086/337875","url":null,"abstract":"The gynoecial micromorphologies of Monotropa uniflora and M. hypopitys are compared to characterize the gynoecial pathway for pollen tube growth. The receptive surface of the concave stigma is restricted to a papillate rim coated with an exudate. An internal transmitting tissue in the stigma joins the papillae with an external transmitting tissue system formed by the lining of the fluted stylar canal that may limit pollen tube growth to specific ovule-bearing placentae. Consequently, pollen tube growth is facilitated in the vicinity of the ovular micropyles.","PeriodicalId":9213,"journal":{"name":"Botanical Gazette","volume":"152 1","pages":"154 - 163"},"PeriodicalIF":0.0,"publicationDate":"1991-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60238462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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