Based on SEM examinations of about 5000 species of seed plants, this is a survey of their epidermal surface characters with an aim to application in taxonomy. Surface characters may be grouped into four categories: (1) Cellular arrangement or cellular pattern. (2) Shape of cells (the “primary sculpture” of a surface). (3) Relief of outer cell walls (the “secondary sculpture” superimposed on the primary sculpture), caused mainly by cuticular striations and superficially visible wall inclusions and wall thickenings. (4) Epicuticular secretions (the “tertiary sculpture” superimposed on the secondary sculpture), i.e. mainly waxes and related substances.

The systematic applicability is discussed for each of these structural groups. Epidermal characters are only slightly influenced by environmental conditions. Their high structural diversity provides most valuable criteria for the classification between species and family level. There is also some evidence for their systematic applicability above the family level.

The possible evolutionary–ecological significance of surface sculpturing is discussed briefly. There is evidence that these features may be seen primarily under the aspects of reduced ability of plants to contaminate and as temperature control mechanisms of the surfaces.

Epidermal and seed surface characters of plants: systematic applicability and some evolutionary aspects

COMPARATIVE EMBRYOLOGY OF ANGIOSPERMS is a review of thedevelopmental processes leading to sexual reproduction inflowering plants. On the basis of embryological data andcertain evidences from other areas of study, it lays specialemphasis on the relationship among and within the familiesand orders of angiosperms. Occasionally, inaccuracies inobservation and interpretation are pointed out, alternativeinterpretations offered, gaps in our knowledge highlighted,and prospects outlined. The text is documented with 36tables, 376 figures, and about 5000 literature citations,which contribute to making this book comprehensive. Besidesstudents and research workers interested in angiospermembyology, taxonomists, plant breeders, agriculturists, andhorticulturists will also find much useful information inthis treatise.

Comparative Embryology of Angiosperms

http://cwd.huck.psu.edu/pdf/Westwood_TIPS_2010.pdf

The evolution of parasitism in plants.

Partial sequences of the nuclear gene encoding the photoreceptor phytochrome A (PHYA) are used to reconstruct relationships within Orobanchaceae, the largest of the parasitic angiosperm families. The monophyly of Orobanchaceae, including nonphotosynthetic holoparasites, hemiparasites, and nonparasitic Lindenbergia is strongly supported. Phytochrome A data resolve six well-supported lineages that contain all of the sampled genera except Brandisia, which is sister to the major radiation of hemiparasites. In contrast to previous plastid and ITS trees, relationships among these major clades also are generally well supported. Thus, the robust phylogenetic hypothesis inferred from the PHYA data provides a much better context in which to evaluate the evolution of parasitism within the group. Ninety-eight species of Orobanchaceae, representing 43 genera, are included and Brandisia, Bungea, Cymbaria, Esterhazya, Nesogenes, Phtheirospermum, Radamaea, Siphonostegia, and Xylocalyx are confirmed as members of Orobanchaceae. The earliest diverging lineage of hemiparasites is identified for the first time; it contains Bungea, Cymbaria, Monochasma, Siphonostegia, and the monotypic Schwalbea, which is federally endangered. This basal clade is marked by the presence of two novel introns. A second, apparently independent gain of one of these introns marks a clade of largely European taxa. There is significant rate heterogeneity among PHYA sequences, and the presence of multiple PHYA in some taxa is consistent with observed ploidy levels.

/pdf/phylogeny-of-the-parasitic-plant-family-orobanchaceae-w0x2euajb6.pdf

Phylogeny of the parasitic plant family Orobanchaceae inferred from phytochrome A.

Parasitic plants are common in natural communities, but are largely ignored in plant community theory. Interactions between parasitic plants and hosts often parallel those between herbivores and plants: both types of consumers display host preferences, reduce host biomass and alter host allocation patterns, modify plant community structure and dynamics, and mediate interactions between host plants and other organisms. In other cases, basic differences in mobility, hormonal and elemental composition and resource capture between plants and animals lead to different effects: parasitic plants have broad host ranges, affect and are affected by host plant physiology because of similar hormonal pathways between parasite and host, do not alter nutrient cycling as extensively as do herbivores, and may simultaneously parasitize and compete with hosts. Many fundamental aspects of the ecology of parasitic plants remain poorly studied, and research to date has been dominated by laboratory studies and studies of crop pests, rather than by studies of natural communities.

Parasitic plants: parallels and contrasts with herbivores.

A study of seed coat sculpturing in Cordylanthus (Scrophulariaceae-Rhinantheae) using the scanning electron microscope (SEM) shows that seed surface patterns are characteristic and constant for a given species or a group of species. Seeds of 23 species were examined and classified into four types (irregularly crested, deeply reticulate, shallowly reticulate, and irregularly striate) based on differences in the reticulated seed coat. Anatomical studies of sections with the light microscope show that the reticular patterns result from enlargement of the epidermal cells of the integument, followed by formation of characteristic wall patterns through lignification. Seed characters furnish useful data for formulating the taxonomy of Cordylanthus both on the sectional and subsectional level and for the delimitation of certain species. Seed coat morphology offers evidence for including the genus Dicranostegia in Cordylanthus and for maintaining C. hispidus and C. palmatus as separate species. The distinctness of two seed coat types within section Cordylanthus suggests two major phylogenetic lines within this section. THE GENUS Cordylanthus comprises about 32 annual species of root hemiparasites which are able to survive the hot summer months in many dry habitats in western North America (Chuang and Heckard, 1971). In the course of systematic studies in Cordylanthus we have explored several lines of investigation to establish a more meaningful and useful taxonomy of the genus. The present study was undertaken with two objectives: (1) to determine the application to the taxonomy of Cordylanthus of differences in seed-surface sculpturing as observed by scanning electron microscopy, and (2) to attempt to understand how the elaborate seed coats originate and develop. The study of seed morphology and development in Cordylanthus has been completely neglected, although some embryological studies have been made of other members of tribe Rhinantheae (for historical accounts see Arekal, 1963; Tiagi, 1966). In his study of seeds of Veronica and allied genera, Thieret (1955) stated: "The Scrophulariaceae are a family embracing a wide variety of seed types. From the study of these types much pertinent taxonomic and evolutionary information 'Received for publication 16 July 1971. 2The work was supported in part by funds from National Science Foundation grant GB-12434 and an Illinois State University research grant. We are especially grateful to the staff of the Electronics Research Laboratory, University of California, Berkeley, for assistance in taking scanning electron micrographs. We are also grateful to Dr. Lincoln Constance, University of California, Berkeley, and Dr. Yoneo Sagawa, University of Hawaii, Honolulu, for their critical reading of the manuscript. can be obtained." Kuijt (1969) also stressed the probability that information from seed morphology and anatomy in parasitic Scrophulariaceae might contribute significantly to the taxonomy of this group. He noted, "Seed anatomy here is an untapped reservoir of systematic information." MATERIALS AND METHODS-Materials used for this study were collected in the field during the summer and fall of 1968, 1969, and 1970. Seeds were also obtained from specimens deposited in the Jepson Herbarium or the University of California Herbarium, both at Berkeley. The collectors and the localities where materials were obtained are shown in Table 1. Voucher specimens of the authors' collections are deposited in the Jepson Herbarium and the Illinois State University Herbarium at Bloomington-Normal. Materials used for anatomical studies were fixed in FAA (Sass, 1958). Dehydration and embedding were carried out by the tertiary butyl alcohol method (Johansen, 1940). All sections were cut at 7-10 /A and stained in aqueous safranin and alcoholic fast green (Sass, 1958). Light photomicrographs were taken with a Zeiss Photomicroscope II. For scanning electron microscopic observations, dried mature seeds were coated with 200-500 A of gold under a conventional vacuum evaporator. Coated seeds were then examined and photographed with the Cambridge Stereoscan Electron Microscope. OBSERVATIONS-Seed coat patterns-Mature seeds of Cordylanthus are reniform (cochlidiospermous), oblong, oblong-ovoid, or rhomboid

Seed coat morphology in cordylanthus (scrophulariaceae) and its taxonomic significance

A B S T R A C T Eight species of Cordylanthus (Scrophulariaceae: tribe Euphrasieae) representing the three major sections of the genus were successfully grown both with and without a host plant, demonstrating that the plants are facultative hemi-parasites capable of completing their life cycle without a host under the favorable conditions of greenhouse culture. The plants are almost certainly parasitic in the wild. Even though haustorial connections were formed by Cordylanthus on the roots of all host plants provided, most species were more vigorous when growing with certain hosts (Quercus, Pinus, Helianthus) than with others (Plantago, Phleum). This indicates a difference in the ability of the parasite to obtain materials successfully from the various plants used as hosts. Natural hosts are inferred for 15 species of Cordylanthus from the presence of associated species in nature. The haustoria are exogenous in origin, being formed by dedifferentiation of several cells in the hypodermal or subhypodermal layers of the rootlets. Anatomically the haustoria differ from those reported for other members of Euphrasieae in having secondary vascular structure and abundant connecting strands. The vascular structure of haustoria is composed mainly of specialized vessel elements. Root-parasitism gives Cordylanthas the ability to grow in arid areas during the summer after most other annuals have died, thus successfully equipping the plants for survival and expansion in western North America. IN THE COURSE of systematic studies in the genus

https://www.jstor.org/stable/pdfplus/2441157.pdf

Observations on root-parasitism in cordylanthus (scrophulariaceae)'

The taxonomy of subtribe Castillejinae, comprising approximately 250 hemiparasitic species principally of western North and South America, is re-evaluated on the generic and sub- generic levels. Based on studies of chromosome number, seed and seed coat morphology, inter- generic hybridizations, and floral morphology, six genera are recognized. The circumscription of three genera remains the same: Clevelandia (one species); Cordylanthus (18 species); Ophiocephalus (one species). The species of Orthocarpus, a highly heterogeneous and probably polyphyletic genus as constituted, are distributed to three genera: 1) Orthocarpus (with affinities to Cordylanthus) is restricted to the type section and subgenus; 2) sects. Castillejoides and Cordylanthoides of subg. Orthocarpus (closely allied to the Castilleja pilosa group) are placed in Castilleja; 3) subg. Triphysaria is raised to generic status. The genus Gentrya is given subgeneric status in Castilleja. The large and expanded genus Castilleja is subdivided into three subgenera: Colacus (with three sections); Gentrya; and Castilleja, which includes the majority of species in the genus. A phylogenetic chart depicts our view of evolutionary relationships within the subtribe. Keys to genera of subtribe Castillejinae and keys to subgenera and sections (excluding sections of subg. Castilleja) of genus Castilleja are provided. New combinations are proposed in Castilleja (two subgenera: Colacus and Gentrya, one section: Oncorhynchus, 11 species and 8 subspecies: C. ambigua subspp. humboldtiensis and insalutata, C.

Generic realignment and synopsis of subtribe Castillejinae (Scrophulariaceae - Tribe pediculareae)

Chromosome numbers are reported for 190 collections ofCastilleja of the Great Basin-Rocky Mountains and adjacent regions in western North America. Polyploidy has played a major role in evolu tion of this genus. Of the 35 taxa represented, 14 are exclusively diploid (n =12). The remaining 21 taxa exhibit polyploidy: eight are tetraploid only, two are octopIoid only, while 11 of the more wide-ranging species have two or more levels of polyploidy. BothC. rhexifolia andC. sulphured have diploid, tetraploid, and octoploid races while the widespreadC. miniata has four (2x, 4x, 8x, and 10x). Where appropriate, the role of polyploidy and hybridization inCastilleja evolution and their relevance to taxonomy are discussed for individual species.

Chromosome numbers, polyploidy, and hybridization in castilleja (scrophulariaceae ) of the Great Basin and Rocky Mountains

Chromosome numbers are reported for 155 collections ofCastilleja representing 54 taxa. The basic haploid number of 12 was found in 34 taxa, but 10 of these also had one or more polyploid levels. The remaining 20 species were strictly polyploid in one or more levels (4X, 6X, 8X, 10X, 12X). The widespread occurrence of polyploidy, along with hybridization, is believed to be largely responsible for the complex morphological variation found within the genus. Specific examples of the role of polyploidy and hybridization in creating this variation are discussed for the following species complexes:C. affinis, C. applegatei, C. miniata, C. peckiana.

L. R. Heckard

Papers

Seed coat morphology in cordylanthus (scrophulariaceae) and its taxonomic significance

Observations on root-parasitism in cordylanthus (scrophulariaceae)'

Generic realignment and synopsis of subtribe Castillejinae (Scrophulariaceae - Tribe pediculareae)

Chromosome numbers, polyploidy, and hybridization in castilleja (scrophulariaceae ) of the Great Basin and Rocky Mountains

Chromosome numbers and polyploidy in Castilleja (Scrophulariaceae)