Unilacunar Nodes Research Articles

Foliar Anatomy of the Family Acanthaceae I. the Tribe Justiceae

The venation type, areole size, vein endings, vein tips and epidermal character have been described in 11 species of the tribe Justiceae of the family Acanthaceae. The features like unilacunar node, a prominent strand, venation patterns, structure of the epidermis, diamesogenous stomata, trichomes, lithocysts, etc. have been found to be useful in taxonomic considerations.

Character evolution and missing (morphological) data across Asteridae.

Our current understanding of flowering plant phylogeny provides an excellent framework for exploring various aspects of character evolution through comparative analyses. However, attempts to synthesize this phylogenetic framework with extensive morphological data sets have been surprisingly rare. Here, we explore character evolution in Asteridae (asterids), a major angiosperm clade, using an extensive morphological data set and a well-resolved phylogeny. We scored 15 phenotypic characters (spanning chemistry, vegetative anatomy, and floral, fruit, and seed features) across 248 species for ancestral state reconstruction using a phylogenetic framework based on 73 plastid genes and the same 248 species. Iridoid production, unitegmic ovules, and cellular endosperm were all reconstructed as synapomorphic for Asteridae. Sympetaly, long associated with asterids, shows complex patterns of evolution, suggesting it arose several times independently within the clade. Stamens equal in number to the petals is likely a synapomorphy for Gentianidae, a major asterid subclade. Members of Lamianae, a major gentianid subclade, are potentially diagnosed by adnate stamens, unilacunar nodes, and simple perforation plates. The analyses presented here provide a greatly improved understanding of character evolution across Asteridae, highlighting multiple characters potentially synapomorphic for major clades. However, several important parts of the asterid tree are poorly known for several key phenotypic features (e.g., degree of petal fusion, integument number, nucellus type, endosperm type, iridoid production). Further morphological, anatomical, developmental, and chemical investigations of these poorly known asterids are critical for a more detailed understanding of early asterid evolution.

Floral development of Kingdonia (Ranunculaceae s. l., Ranunculales)

The flower of Kingdonia has a terminal position, thus the rhizome is sympodial. The floral organs initiate in spiral phyllotaxis. The androecium is centripetal in initiation but the sterile stamens are retarded in development compared with the fertile ones. The apex of the young carpel does not participate in the conduplication. The floral organs have single vascular traces and unilacunar nodes.

ANATOMY AND AFFINITIES OF PENTHORUM

The genus Penthorum L. consists of two species of perennial herbs, P. sedoides of eastern North America and P. chinense of eastern Asia. Penthorum has long been considered intermediate between Crassulaceae and Saxifragaceae. An anatomical study of both species was undertaken to contribute to a better understanding of the relationships of these plants. Prominent anatomical features of Penthorum include: an aerenchymatous cortex and closely‐spaced collateral vascular bundles of stems; one‐trace unilacunar nodes; brochidodromous venation, rosoid teeth bearing hydathodes, and anomocytic stomata of leaves; angular vessel elements with many‐barred scalariform perforation plates and alternate to scattered intervascular pits; thin‐walled non‐septate fiber‐tracheids; abundant homocellular erect uniseriate and biseriate rays; and absence of axial xylem parenchyma. In general, Penthorum possesses neither the morphological nor the anatomical synapomorphies which define Crassulaceae, and features shared with Saxifragaceae are largely symplesiomorphous. Thus Penthorum is probably best classified in the monogeneric Penthoraceae.

Anatomy and Affinities of Penthorum

The genus Penthorum L. consists of two species of perennial herbs, P. sedoides of eastern North America and P. chinense of eastern Asia. Penthorum has long been considered intermediate between Crassulaceae and Saxifragaceae. An anatomical study of both species was undertaken to contribute to a better understanding of the relationships of these plants. Prominent anatomical features of Penthorum include: an aerenchymatous cortex and closely-spaced collateral vascular bundles of stems; one-trace unilacunar nodes; brochidodromous venation, rosoid teeth bearing hydathodes, and anomocytic stomata of leaves; angular vessel elements with many-barred scalariform perforation plates and alternate to scattered intervascular pits; thin-walled non-septate fiber-tracheids; abundant homocellular erect uniseriate and biseriate rays; and absence of axial xylem parenchyma. In general, Penthorum possesses neither the morphological nor the anatomical synapomorphies which define Crassulaceae, and features shared with Saxifragaceae are largely symplesiomorphous. Thus Penthorum is probably best classified in the monogeneric Penthoraceae.

Is the achene a reduced follicle?

Abstract Carpel vasculature in more than 80 follicle and achene bearing species is considered and it is concluded that these 2 basic gynoecial types may not be as closely related as is often supposed. Achenes are from unilacunar nodes, follicles from trilacunar and no intermediate types have been identified.

DIVERSE NODAL ANATOMY OF THE CUNONIACEAE

A comprehensive study of nodal anatomy of the Cunoniaceae has revealed an unusually diverse assemblage of nodal types, including patterns with “split‐lateral” traces previously undescribed for dicotyledons. On the basis of leaf arrangement and nodal vascularization, six distinct nodal conditions are recognized in the family. The trilacunar, three‐trace pattern is the ancestral type from which the multilacunar condition evolved by amplification in the number of lateral traces. The “split‐lateral” condition, distinguished by the fusion of lateral leaf traces of adjacent leaves, or the bifurcation of a single trace, and their association with a “common gap,” probably evolved concomitant with the transition from opposite to whorled leaves. The characteristic interpetiolar stipules of the Cunoniaceae are vascularized by veins originating from lateral leaf traces, or by a combination of complete lateral traces and veins arising from lateral leaf traces. Both Aphanopetalum and Bauera possess unilacunar one‐trace nodes. The most satisfactory family placement of both genera remains uncertain, although the unilacunar nodes of Bauera can reasonably be interpreted as a case of reduction from the trilacunar pattern in response to reduced plant size.

THE MORPHOLOGY AND RELATIONSHIPS OF BARBEYA OLEOIDES

Barbeya, a monotypic genus of dioecious, arborescent dicotyledonous plants from northeast Africa and adjacent Arabia, is usually regarded as having affinities within the Urticales. It is placed either in the Ulmaceae or segregated as a closely related, monotypic family. Leaves are opposite, exstipulate, and vascularized by a single, crescent‐shaped trace from a unilacunar node. Wood anatomy indicates specialization at about the same level as other Urticales. Sieve tube elements of the secondary phloem exhibit highly oblique, compound sieve plates which indicate a low level of evolutionary advancement. The vascularity of the flower is described and compared with other Urticales. Pollen is tricolporate. The relationships of the genus to Moraceae, Ulmaceae, Urticaceae, and Eucommiaceae are discussed. The totality of anatomical and morphological evidence supports the retention of the family Barbeyaceae.

Pharmacognosy of Oldenlandia Corymbosa Linn

AbstractThe detective characters of Oldenlandia corymbosa Linn. a widely used medicinal plant in the Ayurvedic system of India are: - (1) opposite, narrow small leaves, two bases forming a common low sheath; (2) calcium oxalate crystals in the spongy parenchyma cells; (3) rubiaceous stomata; (4) unilacunar node; (5) vessel members of secondary xylem with tails; (5) pollen grains tricolporate with reticulate exine; (6) stomatal index 16-25; (7) vein islet nuber 11-14.28-22.

DEVELOPMENTAL PATTERNS IN STEM PRIMARY XYLEM OF WOODY RANALES. II. SPECIES WITH TRILACUNAR AND MULTILACUNAR NODES

Patterns of early protoxylem strands in vegetative stems of 16 species of woody Ranales representing nine families with trilacunar or multilacunar nodes are illustrated and discussed. The order of differentiation of first protoxylem in all examined species is basipetal. Open, protoxylem strand patterns are more common than closed patterns in these taxa and 11 other woody ranalean species with unilacunar nodes. Protoxylem strand patterns in woody Ranales are diverse, even among species with identical phyllotaxis and nodal anatomy. Pattern similarities of possible taxonomic significance exist, however, between some species of the Annonaceae and Myristicaceae, Hernandiaceae and Lauraceae, and the Canellaceae and Winteraceae. The general diversity of strand patterns in woody Ranales may reflect the high degree of evolutionary isolation among ranalean families. Results of these investigations on stem anatomy of woody Ranales indicate that the two‐trace, unilacunar node is probably not primitive in the Angiospermae. Evidence from this study and others suggests that the primitive node in the Angiospermae, and possibly in all seed plants, is one‐trace, unilacunar or trilacunar. Two‐trace, unilacunar nodal anatomy of the Clerodendron type may have evolved in conjunction with the evolution of decussate phyllotaxis. The protoxylem strand patterns of Illicium and/or Drimys are probably the most primitive of those described in the woody Ranales.

Developmental Patterns in Stem Primary Xylem of Woody Ranales. II. Species with Trilacunar and Multilacunar Nodes

Patterns of early protoxylem strands in vegetative stems of 16 species of woody Ranales representing nine families with trilacunar or multilacunar nodes are illustrated and discussed. The order of differentiation of first protoxylem in all examined species is basipetal. Open, protoxylem strand patterns are more common than closed patterns in these taxa and 11 other woody ranalean species with unilacunar nodes. Protoxylem strand patterns in woody Ranales are diverse, even among species with identical phyllotaxis and nodal anatomy. Pattern similarities of possible taxonomic significance exist, however, between some species of the Annonaceae and Myristicaceae, Hernandiaceae and Lauraceae, and the Canellaceae and Winteraceae. The general diversity of strand patterns in woody Ranales may reflect the high degree of evolutionary isolation among ranalean families. Results of these investigations on stem anatomy of woody Ranales indicate that the two-trace, unilacunar node is probably not primitive in the Angiospermae. Evidence from this study and others suggests that the primitive node in the Angiospermae, and possibly in all seed plants, is one-trace, unilacunar or trilacunar. Two-trace, unilacunar nodal anatomy of the Clerodendron type may have evolved in conjunction with the evolution of decussate phyllotaxis. The protoxylem strand patterns of Illicium and/or Drimys are probably the most primitive of those described in the woody Ranales.

Developmental Patterns in Stem Primary Xylem of Woody Ranales. I. Species with Unilacunar Nodes

Patterns of protoxylem strands in vegetative stems of 11 species representing eight families of woody Ranales are illustrated and discussed. Primary vascular systems of many species examined tend to be pseudosiphonostelic. Protoxylem tissue, however, is discontinuous and consists of discrete strands which develop basipetally. The author assumes that data pertaining to the morphology of these protoxylem strand patterns can be significant in determining phylogenetic relationships among ranalean families and between these and higher angiosperms. The value of the primary vascular system in past taxonomic investigations is also considered. Results of this study indicate that the protoxylem strand patterns of 11 woody ranalean species are diverse even though the species are characterized by identical phyllotaxis and nodal structure.

Anatomical and morphological studies in the Chenopodiaceae. III. The primary vascular system and nodal anatomy

A study of the primary vascular system and nodal anatomy of 32 species of the family Chenopodiaoeae is reported. The results of other workers are integrated and hypotheses regarding probable trends in the evolution of the vascular system are advanced. Basically, the family has a unilacunar node, and the structure of the primary vascular system is classified into three types by reference to the number of leaf traces at a node and their relationships with each other or with cauline bundles within the axis. The Kochia-Bassia type, which is characteristic of Kochia, Bassia, Malacocera, Threllceldia, Babbagia, Enchylaena, Suaeda, and Salsola, is the most primitive and these genera are considered to be closely related. The specialized articulated group, which includes Salicornia and Arthrocnemum, and the third group, the Rhagodia-Atriplex, are more advanced. The relationship between genera within each of these groups is discussed with reference to the vascular anatomy and other morphological features.

MORPHOLOGY AND DICHOTOMOUS VASCULATURE OF THE LEAF OF KINGDONIA UNIFLORA

Foster, Adriance S. (U. California, Berkeley), and Howard J. Arnott. Morphology and dichotomous vasculature of the leaf of Kingdonia uniflora. Amer. Jour. Bot. 47 (8): 684–698. Illus. 1960.—An intensive study of the nodal anatomy, petiolar vasculature and open dichotomous venation of the leaf of Kingdonia has revealed a type of foliar vascular system of unusual morphological and phylogenetic interest. The vascular supply at the nodal level consists of 4 collateral traces which diverge from a single gap into the sheathing leaf base. This type of nodal anatomy is perhaps primitive, and comparisons are made with the unilacunar nodes and the 2‐ and 4‐parted leaf trace systems characteristic of many angiospermous cotyledons and the foliage leaves of certain woody ranalian genera. The petiole of Kingdonia is vascularized by 2 pairs of bundles which represent the upward continuation of the 4 leaf traces. A transition from an even (4) to an odd (3) number of strands occurs near the point of attachment of the 5, lobed, cuneiform lamina segments to the petiole. Each of the 2 abaxial bundles dichotomizes and the central derivative branches fuse to form a double bundle which enters the base of the median lamina segment. The 2 adaxial petiolar bundles diverge right and left into the bases of the paired lateral segments of the lamina. An analogous type of transition from an even to an odd number of veins occurs in many angiospermous cotyledons which develop a definable mid‐vein. But, in Kingdonia, the bundles which enter the bases of the lamina segments give rise to systems of dichotomizing veinlets devoid of “mid‐veins.” Although the majority of the terminal veinlets enter the marginal teeth of the lamina segments, “blind” endings, unrelated to the dentations, occur in all the leaves studied. Typically, all of the vein endings in a given lobule of a lamina segment are derived from the same dichotomous vein system. However, in some leaves, a veinlet dichotomizes directly below a sinus and the branches diverge into the marginal regions of 2 separate lobules. The phylogenetic significance of the occurrence of open dichotomous venation in such an herbaceous angiosperm as Kingdonia is briefly discussed. From a purely morphological viewpoint, the Kingdonia type of venation invites direct comparison with the venation of Sphenophyllum, certain ferns or Ginkgo rather than with any of the known reticulate venation patterns of modern angiosperms. Although the foliar venation of Kingdonia may represent the result of evolutionary reversion, the very rare anastomoses which occur seem primitive in type rather than “vestiges” of a former system of closed venation.

ORIGIN AND DEVELOPMENT OF AXILLARY BUDS: BETULA PAPYRIFERA MARSH. AND EUPTELEA POLYANDRA SIEB. ET ZUCC.

IN THE FIRST part of this study (Garrison, 1949), consideration has been given to the sequence of events associated with the development of axillary buds of Syringa vulgaris L. Emphasis was placed on the origin of bud primordia, vasculation, and the timing and orderly succession of the several developmental phases. This approach is in contrast to earlier investigations in which attentioin has been primarily directed toward certain selected aspects of bud formation; few papers have made reference to the sequence of the various developmental changes. Syringa vulgaris was chosen for the initial studies on axillary bud formation because of the symmetry of its leaf arrangement and because of the anatomical simplicity of its nodal structure, a unilacunar tvpe with one vascular strand from each gap. The present paper is a report on the origin and development of axillary buds of two species with different nodal anatomy: Betula papyrifera Marsh., with trilacunar nodes; and Euptelea polyandra Sieb. et Zucc., with unilacunar nodes in which several vascular strands extend from each gap. Both of these plants have a spiral phyllotaxy (fig. 1, 2). During the spring, summer, and fall seasons of 1945-1946 collections of shoots were made from plants growing in the Arnold Arboretum, Jamaica Plain, Massachusetts. The preparation of the material for study was essentially the same as that described for Syringa vulgaris (Garrison, 1949); buds and twigs were embedded in paraffin, then sectioned transversely and longitudinally at 7 or 10 IL, stained with tannic acid and iron chloride, and counterstained with safranin. OBSERVATIONs.-Betula papyrifera 'Marsh.-A mature bud of Betula papyrifera consists of a short axis bearing three cataphylls2 and six or seven young leaves. The leaves vary in size, grading from those that have enlarged considerably to the primordia that have just emerged at the apex (fig. 3). Associated with each leaf are two stipules which extend behind the leaf and around the axis (fig. 3). Each leaf has a bud primordium in its axil. There are, therefore, bud primordia within a large mature bud; these two generations of buds are referred to here as secondary buds and primary buds, respectively. The description which follows is concerned with the origin of these bud primordia and with the

MORPHOLOGY OF THE VEGETATIVE SHOOT INEPACRIDACEAE

According to Sinnott (I9I4), the Epacridaceae are characterized by the possession of multilacunar nodes, and differ in this respect from all other Ericales, the Clethraceae, Pyrolaceae, Ericaceae, and Diapensiaceae being constantly unilacunar. Bailey & Sinnott (I9I4) quote the family as an example of the association of sheathing leaf-bases with multilacunar nodes. As Hasselberg (1937) has pointed out, the work of these authors loses much of its value by their failure to give the names of the genera and species which they examined. On referring to the account given by Drude (I889), it appears that sheathing leaf-bases occur in only five out of twenty-one genera. The habit of the majority of the family is thoroughly ericoid, which would lead one to expect that the nodes would be unilacunar. I am indebted to Mr R. H. Richens for the information that he had personally observed Epacris ardentissima and Styphelia richei to be unilacunar. In view of the obvious desirability of a more extensive investigation, material was obtained representing twenty-one species belonging to fifteen genera. In this material it has been possible to distinguish three clearly defined types of leaf-base. Typical unilacunar nodes, with narrow leaf-bases, the leaf-scar occupying, at most, about a third of the circumference of the stem, are found in Lebetanthus americanus, Lysinema pungens, Epacris impressa, Styphelia triflora, S. adscendens, S. distans, S. parvifolia, S. acerosa, Monotoca lineata, Acrotriche serrulata, Brachyloma sp., Pentachondra involucrata, Trochocarpa thymifolia, Needhamia pumilio, and Oligarrhena micrantha. A shoot of this type is shown in Fig. I, which represents a species of Styphelia. The same type of structure may be expected to occur also in the genera Prionotes, Woollsia, Archeria, and Conostephium. In Cosmelia rubra (Fig. 2), Sprengelia aristata, and S. incarnata, the base of the leaf embraces the stem, the width of the insertion being actually greater than the circumference of the stem, so that the edges of the leaf-sheath overlap, as in many monocotyledons (Fig. 4). In view of this arrangement it is rather surprising to find only a single foliar trace. Immediately above its point of entry into the leaf, this bundle gives off two branches which run almost horizontally round the base of the sheath. From these girdling bundles spring a number of smaller strands which together form the parallel venation of the leaf sheath and limb. The leaves in these two genera are shed in a very peculiar manner. Separation takes place in the region of the pericycle, so as to cast off not only the leaf but also the entire cortex of the internode below. At this stage the leaf, with its attached frill of stem cortex, can be slipped freely up and down the stem. Owing to the rigidity of the overlapping sheath a leaf may remain in this condition for some time, but a slight lateral pull will suffice to remove it. The collar of stem-cortex is relatively flimsy, and breaks at a touch,