摘要:

A survey for cinnamic and benzoic acids in 22 species representing the 10 extant genera of the Cycadaceae revealed the presence of p‐coumaric, caffeic, ferulic, p‐hydroxybenzoic, protocatechuic, and vanillic acids in all of the species. Two genera had detectable quantities of 2,4‐dihydroxy‐benzoic acid. In addition sinapic acid was detected in two genera, indicating that it has a wider distribution in vascular plants than was previously indicated.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10056.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

A new species of fossil wood,Paraphyllanthoxylon alabamense, is described from silicified logs collected in Macon and Elmore counties from the Tuscaloosa Group, Cretaceous, Cenomanian‐Turonian Stage. All of the logs examined from this area have the same general characteristics and are placed in the new species.Paraphyllanthoxylon alabamenseshows many characteristics intermediate between the two previously described species but it is not identical with either of them. This wood is probably not identical with any living type but it resembles certain members of the Anacardiaceae, Buseraceae, Euphorbiaceae, and Sapindaceae. The large size and abundance of logs ofParaphyllanthoxylon alabamensesuggest that it was a dominant Cretaceous forest tree.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10057.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

Investigation of the morphology and physiology of the mistletoe,Phoradendron tomentosumsubsp.tomentosum, in Texas reveals that the subspecies is differentiated into at least two ecological races, one in north central Texas, the other in south central Texas. The races differ in leaf length/width ratio, fruit diameter, seed set, spike internode length, freeze tolerance, and flavonoid patterns. Clines occur in leaf length/width ratio and fruit diameter between the races, and these characteristics are negatively correlated. The northern race generally exhibits greater freeze tolerance than the southern race. Field observations, herbarium specimens, and a collection of fresh specimens from northeastern Mexico indicate that a third race in the subspecies may exist there. Racial variation within the subspecies appears to permit it to occupy a diversity of habitats. Morphological and physiological patterns within the two Texas races suggest that introgressive hybridization has occurred between them, allowing for the occupation of intermediate habitats.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10058.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

AlthoughUtricularia cornutaMichx. andU. junceaVahl, sympatric in the southeastern United States, have been considered conspecific by various authors, the present biosystematic approach shows them to be separate species. The taxa are seasonally isolated. While both have the same chromosome number (n = 9), strong internal isolation is apparent since artificial hybrids cannot be produced by standard methods. InUtricularia cornutathe mean values of characters studied quantitatively are much higher than those ofU. junceathough the extremes of the ranges may overlap.Utricularia junceahas both cleistogamous flowers and chasmogamous flowers whileU. cornutahas only chasmogamous flowers. The flowers are self‐fertile and apparently are usually, if not always, self‐pollinated, even though they are highly adapted to specialized insect pollinators.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10059.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

By means of electron probe analysis, the effects of significant amounts of accumulation of silicon on the accumulation of calcium, potassium, magnesium, manganese, phosphorous, iron, and sodium in the silica cells of rice leaves are described. The silica cells of both the surfaces of the leaf blade and leaf sheath were studied. Silicon accumulation in the silica cells appears to decrease the amount of accumulation of potassium on both the surfaces of the leaf blade and sheath. The effect of significant amounts of silicon accumulation on the accumulation of other elements in a particular cell varies in different organs or on different surfaces of the organ of the same plant. Magnesium, manganese, iron, and phosphorus could not be detected in the adaxial epidermis of the leaf sheath and magnesium and iron in the adaxial epidermis of the leaf blade. Manganese, magnesium, and phosphorus were not detected in the abaxial epidermis of the leaf blade nor iron in the abaxial epidermis of the leaf sheath. Sodium was not revealed in either surface of the leaf blade and leaf sheath. Possible mechanisms for the effects of silicon accumulation on the accumulation of these elements in rice leaf epidermal cells are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10060.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

Pollen wall development inSorghum bicoloris morphologically and temporally paralleled by the formation of a prominent orbicular wall on the inner tangential surface of the tapetum. In the late tetrad stage, a thin, nearly uniform primexine forms around each microspore (except at the pore site) beneath the intact callose; concurrently, small spherical bodies (pro‐orbicules) appear between the undulate tapetal plasmalemma and the disappearing tapetal primary wall. Within the primexine, differentially staining loci appear, which only develop into young bacula as the callose disappears. Thus, microspore walls are devoid of a visible exine pattern when released from tetrads. Afterwards, sporopollenin accumulates simultaneously on the primexine and bacula, forming the exine, and on the pro‐orbicules, forming orbicules. Channels develop in the tectum and nexine, and both layers thicken to complete the microspore exine. Channeled sporopollenin also accumulates on the orbicules. A prominent sporopollenin reticulum interconnects the individual orbicules to produce an orbicular wall; this wall persists even after the tapetal protoplasts degenerate and after anthesis. While the pollen grains become engorged with reserves, a thick intine, containing conspicuous cytoplasmic channels, forms beneath the exine. Fibrous material collects beneath the orbicular wall. The parallel development and morphological similarities between the tapetal and pollen walls are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10061.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

From extensive cytological, ecological, and morphological studies, it appears that cultivated rye(Secale cerealeL.) originated from weedy products derived from introgression ofS. montanumintoS. vavilovii. Secale vaviloviiappears to have been derived fromS. silvestreas a consequence of chromosomal translocations.Secale silvestrewas, in turn, derived fromS. montanumor a common ancestor.Secale africanum, S. dalmaticum, S. ciliatoglume, andS. kuprijanoviiappear to be only slightly modified isolated populations ofS. montanum. Populations ofS. anatolicumare weedy forms ofS. montanum, genealogically and chromosomally distinct from the weedy annual forms from whichS. cerealearose.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10062.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

Lithospermum caroliniensehas a heteromorphic incompatibility system complemented by self‐compatibility via cleistogamy. Plants typically are either solely chasmogamic or solely cleistogamic. The percentage of cleistogamic plants in northern Illinois and Indiana populations varied from zero to 4.7. However, the percentage seed from self‐fertilization varied from zero to 51.5, because cleistogamic plants produced 1.5 times as many ovules as chasmogamic plants, and the former type averaged 3.4 seeds per flower in contrast to 0.23 in chasmogamic flowers. Interpopulation differences in cleistogamy and self‐fertilization were strongly correlated with plant density, an increase in density being accompanied by increases in the aforementioned features. Most populations had an excess of thrums, but there was no relationship between cleistogamic seed production and thrum:pin ratio.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10063.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

A comparison of shoot apices of runners and rosettes ofNephrolepiswith shoot apices ofAdiantumindicates that a uniform concept of apical organization can be applied throughout. The region directly below the apical initials is designated a “central zone,” by analogy with that found inLycopodium. The central zone is regarded as undifferentiated meristematic tissue rather than incipient vascular tissue.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10064.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

A comparative study of leaf and leaflet abscission inAcer negundoandFraxinus americanawas undertaken with special emphasis on leaflet abscission. Leaf fall in both species is accomplished by orderly, fragmentary abscission of leaflets followed by petiole abscission. Leaflet fall was presaged by differentiation of a separation layer at leaflet bases 10–15 days prior to leaflet fall, without an accompanying protective layer. Anatomical studies of petiole abscission revealed early differentiation of a protective layer followed by differentiation of a separation layer at petiole bases just prior to petiolar fall. Abscission at both sites was facilitated by cell division and dissolution of cell walls within separation layers.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10065.x

出版商:Wiley    

年代:1972

数据来源: WILEY