摘要:

PERUMALLA, C. J., PETERSON, C. A.&ENSTONE, D. E., 1990.A survey of angiosperm species to detect hypodermal Casparian bands. I. Roots with a uniseriate hypodermis and epidermis.Roots of 181 species from 53 families were surveyed to determine the frequency of Casparian bands in hypodermal layers. For six species, inconclusive data were obtained. The roots of the remaining 175 species were divided into three categories on the basis of this survey. In the first, a hypodermis is absent (12 species): no wall modifications were observed in the outer cortex and this region was permeable to the apoplastic dye Cellufluor. In the second, a hypodermis is present, but a hypodermal Casparian band is absent (seven species). In roots of six species, no wall modifications were detected in the hypodermis; the one remaining species had lignified phi thickenings which were permeable to Cellufluor. In the third, both a hypodermis and a hypodermal Casparian band are present (156 species). These Casparian bands consisted of suberin deposits throughout the width of the anticlinal walls of the hypodermis. The tangential walls of the hypodermis were also suberized, indicating that suberin lamellae were probably also present. Hypodermal Casparian bands were found in roots of hydrophytic, mesophytic and xerophytic species and in members of primitive as well as advanced families. The widespread occurrence of these bands (in 89% of the species surveyed) suggests that they were present in the type ancestral to the flowering plants and that this feature has been retained by many species in this group. The epidermal cell walls of the majority of species examined were suberized but were permeable to Cellufluor.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb00176.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

PETERSON, C. A.&PERUMALLA, C. J., 1990.A survey of angiosperm species to detect hypodermal Casparian bands. II. Roots with a multiseriate hypodermis or epidermis.Roots of 25 species which had either a multiseriate hypodermis or a multiseriate epidermis were tested for the presence of a hypodermal Casparian band. All species save one were in the Liliopsida and six were orchids with both soil and aerial roots. Lignosuberized hypodermal Casparian bands were present in all species tested; those with a biseriate hypodermis had bands in both layers and of those with a multiseriate hypodermis, the three species which were tested had bands in every layer. Although Casparian bands can often be recognized by the presence of sinuous walls in longitudinal views of uniseriate hypodermal layers, these sinuosities were not evident in multiseriate hypodermal layers containing Casparian bands. The lack of air spaces, once thought to be a characteristic feature of the hypodermis, did not hold true for some members of the Liliopsida. All walls of the hypodermis were suberized, indicating that suberin lamellae were probably present in addition to Casparian bands. We recommend using the term ‘exodermis’ to refer to a hypodermis which has a Casparian band. Epidermal walls of non‐orchid roots were suberized whereas those of orchids were lignified. Regardless of their type of modification, all epidermal walls were permeable to the apoplastic dye, Cellu

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb00177.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

PERUMALLA, C. J., CHMIELEWSKI, J. G.&PETERSON, C A., 1990.A survey of angiosperm species to detect hypodermal Casparian bands. III. Rhizomes.Rhizomes of ten species of the class Magnoliopsida (Dicotyledoneae) and five species of the class Liliopsida (Monocotyledoneae) were studied to determine whether Casparian bands exist in their hypodermes. The hypodermal walls of rhizomes of all species surveyed appeared autofluorescent under violet light. In sections cleared with NaOH and stained withChelidonium majusroot extract, the radial walls and sometimes the tangential walls of the hypodermis showed bright fluorescence. When the rhizomes were treated with the apoplastic dye, Cellufluor, the dye was initially blocked by the cuticle. When the continuity of the cuticle was disrupted with a needle before treating with Cellufluor, the dye penetrated all the walls of the epidermis and the outer tangential walls of the hypodermis but was blocked by the radial walls of the hypodermis. The walls of the hypodermis stained positively for suberin or suberin and lignin and were resistant to treatment with concentrated sulphuric acid. On the basis of the above tests, it is concluded that Casparian bands are present in the hypodermis of rhizomes of all species surveyed.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb00178.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ONYEKWELU, S. S. C, 1990.Germination, seedling morphology and establishment ofCotnbretum bauchienseHutch.&Dalz. (Combretaceae).Cotnbretum bauchienseis a suffrutex with short, erect, usually herbaceous stems arising from a woody root stock. It appears in savanna soon after fire and (lowers within a few weeks. The fruits germinate in 5–6 days. The germination is cryptogeal. On germination the true radicle and the apparent radicle formed by fused cotyledon stalks push down into the soil, carrying the plumule with them. The cotyledon lamina and part of the fused cotyledon stalks remain above the soil. Both the apparent radicle and the true radicle produce roots. Below the soil at the joint of the apparent radicle and the true radicle the plumule produces 1–3 shoots which grow out to the surface of the soil. The underground portion of the shoot bears scale leaves, from which the plant regenerates when the aerial shoot is damaged by fire. This type of germination is an adaptation that ensures successful establishment in an environment that is subjected to f

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb00179.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

TOBE, H.&PENG, C.‐I, 1990.The embryology and taxonomic relationships ofBretschneidera(Bretschneideraceae).We present the first report on the embryology ofBretschneidera, the only genus of Bretschneideraceae (which are one of 15 glucosinolate‐producing families), to clarify its relationships. EmbryologicallyBretschneiderais characterized by the following features: ovule campylotropous, bitegmic and crassinucellate; outer integument thick, multiplicative and vascularized; embryo sac formation of the Allium type; seed exalbuminous; seed coat ‘exotestal’ with a palisade of columellar, thick‐walled exotestal cells; mesotesta thick with the inner half aerenchymatous. These features suggest thatBretschneiderais distinct from any of the taxonomically related families but resembles both Hippocastanaceae and Sapindaceae (Sapindales) more closely than Moringaceae or Capparaceae (Capparales) which have been considered alternative allies, supporting most of the modern taxonomic treatments that placeBretschneideraas a separate family in S

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb00180.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

WEBB, M. E.&ALMEIDA, M. T., 1990.Micromorphology of the leaf epidermis in taxa of theAgropyron‐Elymuscomplex (Poaceae).A comparative analysis by scanning electron microscopy was carried out on both leaf epidermes (adaxial and abaxial) ofElymus pychnanthus(Godr.) Meld, andAgropyron glaucumRoemer&Schultes.The adaxial epidermes ofE.pychnanthusandA. glaucumare similar in the position and the shape of the long cells, silica bodies and costal and papillate prickles. They differ in the higher number of silica cells inE. pychnanthusand in the presence of intercostal hooks inA. glaucum.The abaxial epidermes of both species are similar in the shape of interstomatal cells, silica bodies and papillate prickles. They differ in the distribution of the stomata and in the contact zones of the long cells.Elymus pychnanthusandA. glaucumdiffer also in the trichomes situated along the margins of the leaf blade.These micromorphological differences, especially those of the abaxial epidermis, are useful taxonomic feature

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb00181.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

VAUGHAN, D. A., 1990.A new rhizomatousOryzaspecies (Poaceae) from Sri Lanka.The confusing taxonomy of the Sri LankanOryza officinaliscomplex is clarified with the recognition of a new rhizomatous species,Oryza rhizomatisVaughan. This species has been found across the dry zone. The other species of the complex in Sri Lanka,O. eichingeri, occurs in moist habitats and is smaller and less common than0. rhizomatis.The new species is described.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb00182.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

JOHANSEN, B., 1990.Incompatibility inDendrobium(Orchidaceae).A unique self‐incompatibility system inDendrobiumis demonstrated by more than 1700 pollination experiments. The majority (72%) of the 61 species that were self‐pollinated showed self‐sterility. In contrast with many other orchid generaDendrobiumshowed high incompatibility in interspecific pollinations. Self‐and interspecific incompatibility is expressed by flower abscission and not by inhibition of pollen germination or pollen tube growth. The incompatibility system is gametophytic and complementary, and it is likely that the auxin content in the pollinia triggers the incompatibility reaction. Microscopical investigations on the detached cells of the stigma (here called eleutherocytes) after compatible and incompatible pollinations, suggest that the incompatibility response is probably controlled by thes

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb00183.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY