Species groups in the genus Ehrharta (Poaceae) in southern Africa

Bothalia ◽  
1987 ◽  
Vol 17 (1) ◽  
pp. 51-65 ◽  
Author(s):  
G. E. Gibbs Russell ◽  
R. P. Ellis
Keyword(s):  
Southern Africa ◽  
Leaf Anatomy ◽  
Leaf Blade ◽  
Winter Rainfall ◽  
The Past ◽  
Centre Of Diversity ◽  
Wide Range ◽  
Species Groups ◽  
Plant Families

Ehrharta Thunb. is a genus of Gondwanaland distribution with its centre of diversity in the winter rainfall Fynbos Biome of southern Africa. In recent subfamily treatments Ehrharta has proved difficult to place satisfactorily, and during the past five years it has been moved between Bambusoideae and Arundinoideae. However, most previous systematic studies using cryptic characters have covered only four taxa out of about 35. The present study includes all African taxa, and demarcates seven species groups on the basis of both spikelet morphology and leaf blade anatomy. Parallelism and/or convergence in vegetative macromorphology within and between the species groups is widespread, and is similar, in some cases, to adaptations found in other plant families in the Fynbos Biome. However, these macromorphological trends are not reflected in the leaf anatomy. Leaf anatomy is generally consistent with the spikelet morphology. Some anatomical differences between the species groups in Ehrharta appear to be as great as differences between taxa of much higher ranks elsewhere in the Poaceae. This wide range of variability may be related to an early divergence of Ehrharteae from other grasses, as suggested by the Gondwanaland distribution, and may explain the difficulty of placing this fascinating yet baffling genus in a subfamily.

Leaf anatomy of the genus Ehrharta (Poaceae) in southern Africa: the Setacea group

Bothalia ◽  
1987 ◽  
Vol 17 (1) ◽  
pp. 75-89 ◽  
Author(s):  
R. P. Ellis
Keyword(s):  
Southern Africa ◽  
Leaf Anatomy ◽  
Leaf Blade ◽  
Anatomical Structure ◽  
The Other ◽  
Leaf Anatomical Structure ◽  
Species Groups ◽  
Distal Cell

The leaf blade anatomy of the taxa of the Setacea group of species of the genus Ehrharta is described and illustrated. This group includes E. rupestris Nees ex Trin. subsp.  rupestris, subsp.  tricostata (Stapf) Gibbs Russell and subsp.  dodii (Stapf) Gibbs Russell, as well as E. setacea Nees subsp.  setacea, subsp.  scabra (Stapf) Gibbs Russell, subsp.  uniflora (Burch, ex Stapf) Gibbs Russell and subsp.  disticha Gibbs Russell. All these taxa share a very characteristic leaf anatomy with inrolled or infolded leaves without keels and have adaxial ribs with interlocking prickles. The chlorenchyma is dense and compact with inwardly projecting invaginations visible in all taxa except  E. setacea subsp.  setacea. In E .  setacea subsp. scabra typical arm cells are present. Abaxial costal and intercostal zones are not differentiated and stomata are absent. The long cells are hexagonal or inflated with sinuous walls. Silica bodies are single or paired and rounded in shape. Small hook-like prickles with short barbs are common. Microhairs with a short, truncated distal cell occur. This leaf anatomical structure differs considerably from that of the other species groups recognized in African  Ehrharta and the Setacea group appears to be more distinct from the other groups than they are from each other.

Panicum simulans (Paniceae, Poaceae), a new species from southern Africa and its leaf anatomy

Bothalia ◽  
1993 ◽  
Vol 23 (1) ◽  
pp. 56-64
Author(s):  
L. Smook ◽  
R. P. Ellis
Keyword(s):  
New Species ◽  
Southern Africa ◽  
Leaf Anatomy ◽  
Light Microscope ◽  
Leaf Blade ◽  
Morphological Characters ◽  
Photosynthetic Pathway ◽  
Surface View ◽  
The Past ◽  
A New Species

Panicum simulans Smook from northern Namibia is formally described. The morphology and leaf blade anatomy in transection and surface view, as observed under the light microscope, are described. The species is compared to others with which it has been confused in the past.  P. simulans can be readily distinguished from  P. novemnerve Stapf and P schinzii Hack, on the basis of both anatomical and morphological characters such as the venation of the lower glume and the photosynthetic anatomy, which is of the NAD-me subtype of the C4 photosynthetic pathway. On this basis it appears that P simulans is closely allied to the P. coloratum L. group of species and should be placed in section Panicum of subgenus Panicum.

The taxonomic position of C3 and C4 Alloteropsis semialata (Poaceae) in southern Africa

Bothalia ◽  
1983 ◽  
Vol 14 (2) ◽  
pp. 205-213 ◽  
Author(s):  
G. E. Gibbs Russell
Keyword(s):  
Southern Africa ◽  
Leaf Blade ◽  
Morphological Characters ◽  
Taxonomic Position ◽  
Grass Species ◽  
The Past ◽  
Photosynthetic Pathways ◽  
Voucher Specimens

Alloteropsis semialata (R. Br.) Hitchc. sensu Chippindall (1955) and Clayton (in press) is the only known grass species in which elements with both non-Kranz and Kranz leaf blade anatomy, and therefore with C3 and C4 photosynthetic pathways are included. In the past, two taxa had been recognized, but the characters used to separate them were found to be unreliable, so they were united. However, study of voucher specimens for anatomical and physiological work has shown that C3 and C4 taxa may be separated on the basis of morphological characters that differ from those considered in the past. Therefore, two taxa are again recognized, this time at the rank of subspecies, and the name  Alloteropsis semialata subsp. eckloniana (Nees) Gibbs Russell  stat. nov. is published.

scholarly journals Vegetation geographical patterns as a key to the past, with emphasis on the dry vegetation types of South Africa

Bothalia ◽  
1983 ◽  
Vol 14 (3/4) ◽  
pp. 405-410 ◽  
Author(s):  
M. J. A. Werger
Keyword(s):  
Southern Africa ◽  
Woody Species ◽  
Dwarf Shrub ◽  
Strongly Correlated ◽  
Cam Plants ◽  
Winter Rainfall ◽  
Geographical Patterns ◽  
The Past ◽  
Montane Vegetation ◽  
Cape Fynbos

Southern Africa is characterized by a highly diversified vegetational cover with extremes as contrasting as desert, tropical forest, alpine grassland, or mediterranean type scrub, and many other types in between. This vegetational pattern is strongly correlated to the climatological pattern. It is therefore likely that past changes in climate can still be partly traced in the vegetational pattern, particularly in geographical anomalies, and that study of these patterns provides complementary evidence to palynological research. The following anomalies in the vegetational pattern are briefly discussed: 1. island-wise occurrence of Afro-montane vegetation on mesic, sheltered sites in the southern Sudano- Zambezian Region, in particular in the Highveld grassland/False Karoo transition area; 2. similar westward occurrence of Sudano-Zambezian scrub patches in the Karoo-Namib Region near the Orange/Vaal confluence; 3. scattered occurrence of Sudano-Zambezian woody species in a matrix of Karoo-Namib vegetation in the marginal Karoo-Namib Region; 4. island-wise occurrence of frost-tolerant, dry, karroid dwarf shrub vegetation of predominantly C,-plants on isolated peaks in the winter rainfall area of Namaqualand; 5. peculiar patchy distribution of some succulents in wide areas of climatically rather homogeneous, succulent dwarf shrub vegetation of predominantly CAM-plants in the escarpment area of Namaqualand. a pattern reminiscent of that in many Cape fynbos species. Interpretation of these patterns logically leads to the conclusion that these result from a previously wetter, a previously cooler, or a previously wetter and cooler climate, respectively, over the parts of southern Africa under discussion. This conclusion is compared with published palynological views.

Taxonomy and leaf anatomy of the genus Ehrharta (Poaceae) in southern Africa: the Dura group

Bothalia ◽  
1988 ◽  
Vol 18 (2) ◽  
pp. 165-171 ◽  
Author(s):  
G. E. Gibbs Russel ◽  
R. P. Ellis
Keyword(s):  
Southern Africa ◽  
Leaf Anatomy ◽  
Species Group ◽  
Anatomical Relationship ◽  
Species Groups

The Dura species group in the genus Ehrharta Thunb. is differentiated morphologically by the perennial habit and the very large, awned, subglabrous spikelets and anatomically by the occurrence of tanniniferous cells and wax platelets obscuring the stomatal pores. The Dura group consists of two species, E. dura Nees ex Trin. and E. microlaena Nees ex Trin., which occur only in Mountain Fynbos. The group shows no clear morphological or anatomical relationship with other species groups in the genus in southern Africa.

Three cryptic new species of Aristea (Iridaceae) from southern Africa

Bothalia ◽  
2005 ◽  
Vol 35 (1) ◽  
pp. 1-6
Author(s):  
P. Goldblatt ◽  
A. P. Dold ◽  
J. C. Manning
Keyword(s):  
New Species ◽  
Southern Africa ◽  
Summer Rainfall ◽  
Field Work ◽  
The Past ◽  
Centre Of Diversity ◽  
Flowering Stem ◽  
Sub Saharan ◽  
Three New Species ◽  
Pollen Shed

Field work in southern Africa over the past several years has resulted in the discovery of three new species of the sub- Saharan African and Madagascan genus Aristea Aiton, which now comprises some 53 species. Aristea has a pronounced centre in southern Africa and a centre of diversity in the winter rainfall zone of the subcontinent, where all three new species occur, one extending eastward into the adjacent southern edge of the summer rainfall zone. All three novelties have been collected in the past but were confused with related species. A elliptica (subgenus Eucapsulares), confused in the past with A. pusilla (Thunb.) Ker Gawl., has a more robust habit, usually with 4 or 5 flower clusters per flowering stem, pale blue flowers, smooth ellipsoid seeds with flattened surface cells, and pollen shed as monads, whereas A. pusilla usually has 1-3 flower clusters per flowering stem, dark blue flowers, pollen shed as tetrads, and globose seeds with faint foveate sculpturing and colliculate surface cells. A. nana (also subgenus  Eucapsulares), known from few collections, and also confused with A. pusilla or A. anceps Eckl. ex Klatt. has the unbranched and leafless flowering stem of the latter but has large green floral spathes, flowers borne on long pedicels, and lacks a leaf subtending the single terminal flower cluster in contrast to nearly sessile flowers in A. pusilla and A. anceps, and in the latter, dry, rusty spathes. A. cistiflora (subgenus Pseudaristea) closely resembles A. teretifoha Goldblatt J.C.Manning but has linear to narrowly sword-shaped leaves and ± secund flowers with the outer tepals only slightly smaller than the inner and with small, dark brown markings at the bases of all the tepals. In contrast, A. teretifolia has narrower, sometimes terete leaves and flowers held upright with the outer tepals notice-ably smaller than the inner and bearing dark markings covering the lower half, whereas the inner tepals are unmarked.

Leaf anatomy of the South African Danthonieae (Poaceae). V. Merxmuellera macowanii, M. davyi and M. aureocephala

Bothalia ◽  
1981 ◽  
Vol 13 (3/4) ◽  
pp. 493-500
Author(s):  
R. P. Ellis
Keyword(s):  
Light Microscopy ◽  
South African ◽  
Vascular Bundle ◽  
Leaf Anatomy ◽  
Related Species ◽  
Leaf Blade ◽  
Vascular Bundles ◽  
The South ◽  
Species Groups

Transverse sections and abaxial epidermal scrapes, of herbarium and freshly fixed leaf blade material, of Merxmuellera macowanii (Stapf) Conert, M. davyi (C. E. Hubb.) Conert and M. aureocephala (J. G. Anders.) Conert, were examined using light microscopy. The leaf anatomy o f these three species is very similar in all respects with the exception o f certain  M. aureocephala specimens. In addition, the anatomy indicates a relationship between these three species and M. disticha (Nees) Conert. This group of species differs anatomically from M. stricta (Schrad.) Nees, and related species such as  M. drakensbergensis (Schweick.) Conert and  M. stereophylla (J. G. Anders.) Conert, in the sequence of vascular bundles along the width of the leaf blade and associated characters. However, the M. aureocephala specimens, not having the  M. disticha type of vascular bundle arrangement, anatomically resemble the M. stricta group of species, and M. aureocephala appears to be intermediate between these two species groups.resemble the M. stricta group of species, and M. aureocephala appears to be intermediate between these two species groups.

Leaf anatomy of the genus Ehrharta (Poaceae) in southern Africa: the Villosa group

Bothalia ◽  
1987 ◽  
Vol 17 (2) ◽  
pp. 195-204
Author(s):  
R. P. Ellis
Keyword(s):  
Southern Africa ◽  
Leaf Anatomy ◽  
Leaf Blade ◽  
Species Group ◽  
Anatomical Evidence

The leaf blade anatomy of Ehrharta villosa Schult. f. var.  villosa, var.  maxima Stapf and  E. thunbergii Gibbs Russell is described and illustrated. These three taxa, constituting the Villosa species group, share a diagnostic leaf anatomy distinguished by the absence of a distinct midrib, adaxial semi-radiate mesophyll with the abaxial chloren- chyma palisade-like in arrangement, rectangular long cells and the stomatal apertures which are overlapped by four cuticular flanges projecting from the two adjacent interstomatal cells. These combined attributes characterize this species group, and the stomatal flanges are unique to this group in the genus Ehrharta Thunb. Microhairs are absent in  E. villosa but are present in  E. thunbergii which also possesses abaxial prickles and plentiful, rounded silica bodies not associated with cork cells as in  E. villosa. These two taxa can. therefore, be separated anatomically. Nevertheless, they share many features and are undoubtedly closely related and their classification in the same species group is substantiated by the anatomical evidence presented in this paper.

Optical Properties of HVEM Accelerators

1975 ◽  
Vol 33 ◽  
pp. 180-181
Author(s):  
A. Strojnik ◽  
J.W. Scholl ◽  
V. Bevc
Keyword(s):  
Optical Properties ◽  
Electron Accelerator ◽  
Systematic Investigation ◽  
Electron Source ◽  
High Brightness ◽  
The Past ◽  
Wide Range ◽  
Optical Behavior

The electron accelerator, as inserted between the electron source (injector) and the imaging column of the HVEM, is usually a strong lens and should be optimized in order to ensure high brightness over a wide range of accelerating voltages and illuminating conditions. This is especially true in the case of the STEM where the brightness directly determines the highest resolution attainable. In the past, the optical behavior of accelerators was usually determined for a particular configuration. During the development of the accelerator for the Arizona 1 MEV STEM, systematic investigation was made of the major optical properties for a variety of electrode configurations, number of stages N, accelerating voltages, 1 and 10 MEV, and a range of injection voltages ϕ0 = 1, 3, 10, 30, 100, 300 kV).

Pursuit of the Abscopal Effect

2020 ◽  
Vol 04 (04) ◽  
pp. 369-372
Author(s):  
Paul B. Romesser ◽  
Christopher H. Crane
Keyword(s):  
Tumor Immunology ◽  
Antitumor Immunity ◽  
Clinical Success ◽  
Immune Recognition ◽  
Immune Modulators ◽  
Cancer Subtypes ◽  
The Past ◽  
Tumor Irradiation ◽  
Wide Range ◽  
Tumor Recognition

AbstractEvasion of immune recognition is a hallmark of cancer that facilitates tumorigenesis, maintenance, and progression. Systemic immune activation can incite tumor recognition and stimulate potent antitumor responses. While the concept of antitumor immunity is not new, there is renewed interest in tumor immunology given the clinical success of immune modulators in a wide range of cancer subtypes over the past decade. One particularly interesting, yet exceedingly rare phenomenon, is the abscopal response, characterized by a potent systemic antitumor response following localized tumor irradiation presumably attributed to reactivation of antitumor immunity.

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