EARLY CRETACEOUS TETRADS,ZONASULCULATE POLLEN,AND WINTERACEAE. I. TAXONOMY,MORPHOLOGY, AND ULTRASTRUCTURE

Ulcerate pollen tetrads from the late Barremian-early Aptian of Gabon, named Walkeripollis gabonensis gen. et sp. nov., resemble pollen of extant Winteraceae but have finer sculpture and a weakly calymmate tectum, like tetrads reported from the late Aptian-Albian of Israel. Scanning and transmission electron microscopy reveal additional winteraceous features (tall muri, short columellae, ring of endexine around the ulcus), plus segmented muri recalling the reticulate, zonasulculate to inaperturate genus Afropollis, which is abundant in the Aptian-Albian of Northern Gondwana. Afropollis also resembles Winteraceae in having tall muri and short columellae, but it has a thicker endexine. The new zonasulculate genus Schrankipollis, including S. mawhoubensis (Schrank) comb. nov. from the Aptian of Egypt and S. microreticulatus (Brenner) comb. nov. from the Potomac Group of Maryland, resembles Afropollis in structure of its muri but differs in its elliptical shape, finer reticulum, and restricted endexine.     

Elymus sibiricus, E. nutans 和 E. burchan-buddae 的形态学鉴定及其染色体组亲缘关系的研究

为了进一步研究Elymus sibiricus L.、E．nutans Griseb．和E．burchan-buddae(Neuski)Tzelev [＝Roegneria nutans(Keng)Keng]的外部形态差异及其系统学关系,本文对这三种植物的6个穗部形 态性状进行了观测和比较,并对这三个Elymus种进行了种间杂交及杂种F1的减数分裂染色体配对行 为的分析研究。结果表明：这三个Elymus种的穗长及颖长等性状均变异很大,而内稃的长、宽则变异 不大并具有明显的种间差异。E. nutans×E．barchan-buddae及E.nutans×E．sibiricus的杂种F1均完 全不育,减数分裂不规则。E．nutans×E．burchan-buddae杂种F1的减数分裂构型为：7.70I+13.40 Ⅱ+0.06Ⅲ+O.08 Ⅳ,而E．sibiricus×E．nutans杂种F1的构型为11.98 Ⅰ+9.61Ⅱ+O.64Ⅲ+0.39 Ⅳ+0.01V。由本实验的形态学和细胞学的研究结果得出以下结论：1．利用内稃形态性状结合穗部 其它性状的差异能对这三个物种进行较准确的鉴定;2．E．nutans与E.burchan-buddae的亲缘关系较 近,而E．nutans与E．sibiricus的亲缘关系则较远;3. E,burchan-buddae×E．nutans的杂种Fl中存在着染色体配对控制因子。     

CHROMOSOMES AND CROSSING BEHAVIOR OF HIBISCUS CANNABINUS,H. ACETOSELLA,AND H. RADIATUS

Menzel , Margaret Y. (Florida State U., Tallahassee), and F. D. Wilson . Chromosomes and crossing behavior of Hibiscus cannabinus, H. acetosella, and H. radiatus. Amer. Jour. Bot. 48(8): 651–657. Illus. 1961.—Chromosomes of diploid H. cannabinus L. (kenaf) form 18 bivalents at metaphase I. In autotetraploid H. cannabinus (2n = 72), more than 50% of the chromosomes pair as trivalents or quadrivalents. In the tetraploid species H. radiatus Cav. and H. acetosella Welw. ex Hiern (H. eetveldeanus De Wild. & Dur.) (2n = 72), only 4% of the chromosomes pair as multivalents and the rest pair as bivalents. Vigorous, highly fertile F₁ hybrids between H. acetosella and H. radiatus are easily obtained, show complete chromosome pairing, and give rise to a freely segregating, vigorous, fertile F₂: apparently the parental species have similar genome constitutions and are closely related. Chromosome pairing in the triploid hybrids of H. radiatus and H. acetosella with H. cannabinus, in hexaploids obtained by doubling the chromosome number of H. acetosella-cannabinus F₁, and in pentaploid and tetraploid backcrosses of the hexaploids to H. cannabinus shows that the tetraploid species each contain 1 genome (A) very similar to, but not identical with, that of H. cannabinus and 1 dissimilar genome (B). Morphology, fertility, and other characteristics of the various hybrids are discussed in connection with the problem of recombining the resistance to root-knot nematodes found in the tetraploid species with the desirable fiber properties of H. cannabinus.     

HYBRIDS AND GENOME RELATIONS OF HIBISCUS SABDARIFFA,H. MEEUSEI,H. RADIATUS AND H. ACETOSELLA

Chromosome pairing was studied in the following hybrids: Hibiscus radiatus-meeusei (tetraploid F₁), H. sabdariffa-meeusei (tetraploid F₁ and spontaneous allooctoploid F₂), and hexaploid H. acetosella-(sabdariffa-meeusei). Genome constitutions of the species adduced from these data are symbolized as follows: H. radiatus and H. acetosella, AABB; H. meeusei, AAXX; H.sabdariffa, XXYY or AAYY.     

ULTRASTRUCTURE AND SYSTEMATICS OF TWO NEW FRESHWATER RED CRYPTOMONADS, STOREATULA RHINOSA, SP. NOV. AND PYRENOMONAS OVALIS, SP. NOV.

The ultrastructure and systematics of two red colored freshwater cryptomonads, Storeatula rhinosa , sp. nov. and Pyrenomonas ovalis , sp. nov., are described for the first time. Storeatula, which had been described from marine waters only, has a single inner periplast sheet and a fibrous surface periplast component. Cells lack a furrow but possess a gullet, a bilobed chloroplast connected by a pyrenoid and a nucleomorph located in an indentation of the pyrenoid. This freshwater Storeatula possesses the same general features as the marine species, but it has a contractile vacuole and lacks the lobed chloroplast of S. major. P. ovalis has the generic characteristics described for marine species of Rhodomonas. These characteristics include a short furrow, a deep gullet, square inner periplast plates with beveled corners, a slightly fibrillar surface periplast component, a single chloroplast with two lobes connected by a pyrenoidal bridge and a nucleomorph located in an indentation of the pyrenoid.     

PALYNOLOGY AND SYSTEMATICS OF THE LYTHRACEAE. III. GENERA PHYSOCALYMMA THROUGH WOODFORDIA,ADDENDA, AND CONCLUSIONS

Pollen of the 27 genera presently recognized as comprising the family Lythraceae have been surveyed with light microscopy and scanning and transmission electron microscopy. Results for five genera (Physocalymma, Pleurophora, Rotala, Tetrataxis, Woodfordia), in addition to Duabanga, Sonneratia, and Punica (assigned to the Lythraceae in some classifications), are presented here; the remaining genera were treated previously in the series. The family is revealed as the most diverse palynologically of the order Myrtales. The most simple pollen type and the one common to the largest number of genera is prolate-spheroidal to prolate; tricolporate, without pseudocolpi; psilate, scabrate or finely verrucate; and 16–28 μm or less in length. Specializations include oblate grains, development of pseudocolpi (three or six in number), diversification of exine sculpturing, broadening of the colpal and pseudocolpal areas, and reduction in the conspicuousness of the colpi. Pollen evidence provides qualified support for inclusion of Punica in the Lythraceae, the generalized nature of the pollen tempering the conclusion, and little support for inclusion of Sonneratia and Duabanga in the family. Completion of the survey provides a data base of pollen characters that will be integrated in future studies with other evidence into an overall phenetic and cladistic assessment of the family leading to production of a more natural classification.