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General Key to the Families

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GENERAL KEY TO THE FAMILIES I. SUBKINGDOM PTERIDOPHYTA, FERN PLANTS Plants with typically distinct alternation of generations, the leafy plant (sporophyte) reproducing by non-sexual spores. Spores developing prothallia or flat plates of tissue (gametophyte) bearing antheridia (containing male cells or sperms) and archegonia (containing a female cell or oospore). Oospore ferti- lized in the presence of water by a self-motile sperm. Flowers or seeds none. Ours herbs. Stems not jointed or rush-like. Stems small in comparison with the leaves, often very short, usually un- branched. Land plants, or at least essentially terrestrial; sporangia borne on the lower side or edges of the leaves; spores all of one kind and size (isosporous). Leaf 1, erect in the bud; sporangia borne in spikes, the spikes simple or branched, not green. .OPHIOGLOSSACEAE, p. 25. Leaves several to numerous, circinate in the bud, often large and characteristically much-divided; sporangia borne in clus- ters (sori) on the back or margin of green leaves POLYPODIACEAE, p. 26. Aquatic or subaquatic plants; sporangia and spores of 2 kinds. Sporangia borne in special conceptacles; stems not corm-like. Plants floating in water; leaves minute, entire or 2-lobed. .. SALVINIACEAE, p. 39. Plants rooting in mud; leaves 4-foliolate or filiform MARSILEACEAE, p. 39. Sporangia borne in the leaf-axils; leaves awl-like or linear, clus- tered on a flattened or corm-like stem. .ISOETACEAE, p. 43. Stems more or less elongated, freely branching, closely clothed or imbricated with small awl-like or scale-like leaves; sporangia borne in or near the leaf axils. Spores of one kind LYCOPODIACEAE, p. 41. Spores of two kinds SELAGINELLACEAE, p. 41. Stems jointed or rush-like, hollow, the reduced leaves joined into a toothed sheath at the nodes; sporangia borne on the under side of the scales in a terminal cone-like spike; spores of 1 kind EQUISETACEAE, p. 39. II. SUBKINGDOM SPERMATOPHYTA, SEED PLANTS Plants without distinct alternation of generations, the sexual phase (game- tophyte) much reduced and parasitic upon the sporophyte; egg-cell fertilized through the intervention of the pollen-tube, the developed embryo forming a resting body called a seed. CLASS 1. GYMNOSPERMAE, CONE-BEARING PLANTS Ovules and seeds borne naked on the surface of a scale; stamens and ovules in catkin-like clusters; cotyledons 2 to 17; cone-bearing trees or shrubs, all of ours evergreen; true flowers none; leaves needle-like, narrowly linear, awl-like or scale-like. Trees, rarely shrubs, with resin. Fruit a woody cone (soft and berry-like in Juniperus), containing several to many seeds; ovules in catkins. Cone-scales imbricated, with a conspicuous or minute bract at base on lower side; leaves needle-like or narrowly linear; seeds 2 to each scale, bearing a thin wing PINACEAE, p. 44. Cone-scales without bracts. 21 22 KEY TO THE FAMILIES Leaves narrowly linear and 2-ranked in flat sprays, or lanceolate or awl-like and disposed all around the branchlet; cone-scales not imbricated, ending in broad flattish summits; seeds 2 to 9 to each scale, not winged TAXODIACEAE, p. 54. Leaves minute and scale-like, thickly clothing the ultimate branch- lets; cone-scales imbricated, or with broad flattish sum- mits and not imbricated; seeds 1 to several to each scale, winged or wingless CUPRESSACEAE, p. 55. Fruit berry-like or drupe-like, one-seeded; ovules solitary; leaves narrowly linear, in flat sprays TAXACEAE, p. 59. Shrubs without resin; deserts GNETACEAE, p. 60. CLASS 2. ANGIOSPERMAE, FLOWERING PLANTS Ovules borne in a closed sac or ovary, which becomes the fruit and encloses the seed; cotyledons 1 or 2; plants wirli true flowers, typically with an abbreviated stem (receptacle) bearing regular whorls of perianth parts, stamens, and pistils. SUB-CLASS 1. MONOCOTYLEDONEAE Leaves parallel-veined (except Trillium) ; parts of the flower usually in 3s, rarely in 2s, 4s or 5s; vascular bundles scattered irregularly through the pithy tissue, not in rings or annual layers; embryo with 1 cotyledon; perennial herbs commonly with rootstocks or bulbs, or annuals, or a few trees or shrubs. A. PERIANTH NONE OR CALYX-LIKE WITH SCALE-LIKE DIVISIONS; PARTS OP THE FLOWER MOSTLY UNEQUAL IN NUMBER; CARPELS 1 TO SEVERAL, DISTINCT, OR SOMETIMES UNITED BUT SEPARATING AT MATURITY. 1. Flowers not in the axils of dry chaffy bracts; ovary superior; herbs. Leafless minute aquatics, the stems represented by leaf-like floating fronds LEMNACEAE, p. 194. Leafy plants. Immersed aquatics; leaves filiform or linear, or some floating ones with broad blades; flowers inconspicuous, naked or with a very small calyx, borne on a spike or spadix; stamens 1 to 4; ovaries 1 to 4. NAIADACEAE, p. 63. Plants of marshes or rising out of water. Flowers monoecious; reed-like plants with linear leaves. Inflorescence a dense cylindrical spike. TYPIIACEAE, p. 61. Inflorescence a dense globose head SPARGANIACEAE, p. 62. Flowers perfect, rarely polygamous, in racemes or spikes. Inflorescence with a spathe; calyx none; stamens 6 ARACEAE, p. 193. Inflorescence naked; calyx of 6 (or 3) distinct sepals, or none; stamens 6 or 1 JUNCAGINACEAE, p. 68. 2. Flowers in the axils of dry chaffy bracts, arranged in spikes or spikelets. Stems mostly terete and hollow; leaves in 2 rows; sheaths mostly split open oppo- site the blade; bractlets 2 to each flower; fruit a grain (seed mostly adnate to the pericarp) GRAMINEAE, p. 72. Stems mostly triangular, solid; leaves in 3 rows; sheaths entire; ligule obsolete or minute; bractlet 1 to each flower; fruit an achene (seed free from the pericarp) CYPERACEAE, p. 144. B. PERIANTH ALWAYS PRESENT, ITS SEGMENTS IN 2 SERIES, RARELY IN 1, OFTEN COROLLA-LIKE; PARTS OF THE FLOWER USUALLY EQUAL IN NUMBER; CARPELS UNITED INTO ONE COMPOUND OVARY (EXCEPT ALISMACEAE). Inflorescence without a spathe. Pistil 1. Ovary superior; perianth regular; stamens 6, sometimes 3 or 4. Perianth-segments distinct, green or brown, not petal-like; flowers small or minute; rush-like plants.... JUNCACEAE, p. 196. KEY TO THE FAMILIES 23 Perianth-segments distinct or partly united, at least the inner petal- like; flowers mostly showy; plants not rush-like LILIACEAE, p. 208. Ovary inferior; flowers perfect, mostly conspicuous; perennial. Perianth regular; ovary 3-celled. Stamens 6; leaves (in ours) fleshy, in a basal rosette AMARYLLIDACEAE, p. 252. Stamens 3; leaves 2-ranked, sword-like and sheathing IRIDACEAE, p. 253. Perianth irregular; stamens 1, rarely 2; ovary 1-celled; leave9 sheathing, often reduced to scales. ..ORCHIDACEAE, p. 255. Pistils several, distinct, 1-celled, superior, becoming achenes; perianth of 3 sepals and 3 petals; stamens 6 to many ALISMACEAE, p. 69. Inflorescence with a spathe; pistil 1. Herbs. Ovary inferior; 1 to 3-celled; stamens 3 to 12; aquatic plants; leaves opposite or whorled HYDROCHARITACEAE, p. 72. Ovary superior. Aquatic plants; leaves ribbon-like PONTEDERIACEAE, p. 195. Marsh or bog-perennials; leaves broad ARACEAE, p. 193. Trees; flowers on a spadix or fleshy spike PALMACEAE, p. 193. SUB-CLASS 2. DICOTYLEDONEAE Leaves commonly netted-veined; parts of the flower mostly in 4s or 5s; vascular bundles in a ring around a central pith, the stem, when perennial, increasing in girth by annual layers; embryo with 2 cotyledons; herbs, shrubs or trees. I. APETAXOUS DIVISION. Corolla none; calyx present, herbaceous or often petal-like, sometimes none. A. Flowers monoecious or dioecious, one or both kinds in catkins; trees or shrubs. 1. Leaves opposite. Flowers dioecious. Catkins erect; maritime shrub BATIDACEAE, p. 340. Catkins drooping; montane shrubs GARRYACEAE, p. 731. Flowers monoecious; ovary superior, 2 or 3-celled BDXACEAE, p. 606. 2. Leaves alternate. Both kinds of flowers in catkins. Flowers 1 to each scale or bract; calyx none. Fruit a 1-celled many-seeded capsule; seeds with a coma; flowers dioe- cious; foliage deciduous SALICACEAE, p. 261. Fruit waxy-coated, berry-like; flowers monoecious or dioecious; foliage evergreen or deciduous MYRICACEAE, p. 279. Flowers 2 or 3 to each scale or bract; calyx present; staminate catkins long. pendulous, the pistillate small, spike-like, maturing into a woody cone containing small nutlets BETULACEAE, p. 269. Only the staminate flowers in catkins, the pistillate flowers solitary or clustered, rarely in catkins. Leaves simple. Fruit a nut set in a scaly cup or bur (acorn or chestnut) FAGACEAE, p. 271. Fruit a nut enclosed in a leafy tubular involucre. .CORYLACEAE, p. 270. Leaves pinnately compound; fruit a nut with a fibrous coat JUGLANDACEAE, p. 279. 24 KEY TO THE FAMILIES B. Flowers perfect or unisexual, not in catkins. 1. OVARY SUPERIOR, THAT IS, FREE PROM THE CALYX. a. Flowers hypogynous. * Calyx present; corolla none. Pistil one. Ovary 1-celled; styles or stigmas 1 or more than one. Fruit in dehiscent (circumscissile in some Amaranthaceae). Fruit dry (an achene or utricle) ; stamens 1 to 9. Herbage with stinging hairs; flowers very small, monoecious, in a catkin-like inflorescence; sepals 4; stamens 4; herbs URTICACEAE, p. 280. Herbage without stinging hairs. Plants commonly scurfy, of alkaline or maritime habitat; sepals herbaceous, or in unisexual flowers, tha pistillate without calyx and enclosed by 2 bracts; bractlets none; stamens 1 to 5; leaves alternate, rarely opposite or leafless; stipules none CHENOPODIACEAE, p. 319. Plants not scurfy. Calyx not tubular; leaves alternate or opposite or basal. Fruit a triangular or lenticular achene; calyx colored or herbaceous. 5 or 6-cleft or -parted; flowers with or without bract- lets ; stamens 3 to 9; stipules present or none POLYGONACEAE, p. 286. Fruit a utricle; calyx scarious, 5 or 3-cleft or -parted; flowers with bractlets; stamens 3 to 5 (rarely 1); stipules none AMARANTHACEAE, p. 333. Calyx tubular, corolla-like, the base of the tube hard- ening and enclosing the achene; stamens 3 to 5; leaves opposite, without stipules NYCTAGINACEAE, p.
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  • Significance of Leaf Orientation and Bract in Seed Yield in Sunflower

    Significance of Leaf Orientation and Bract in Seed Yield in Sunflower

    SIGNIFICANCE OF LEAF ORIENTATION AND BRACT IN SEED YIELD IN SUNFLOWER G. C. SRIVASTAVA, P. S. DESHMUKH AND D.P.S. TOMAR Division of Plant Physiology Indian Agricultural Research Institute New Delhi-110012. Received on September 13, 1976 SUMMARY Defoliation experiments in sunflower (Helianthus annus L. var. EC 68413) have been shown that seed yield and the size of head are built up mainly by the photo­ synthate from the upper leaves and the bracts proximate to head. The contribution from the leaves varied with their position on the stem. It was noticed to be the highest from the top 6 to 8 leaves followed by middle leaves and least from the leaves at the bottom. INTRODUCTION Investigations on the physiology of grain production in crop plants have highlighted the importance of different plant parts as the coutributors of organic assimilates. In this context, orientation of the leaves in plant canopy plays a signifi­ cant role. It is well documented that in many grain crop the upperleaves translocate their photosynthates (assimilates) mostly to the developing grain and stem, the lower leaves to the root and tillers and the leaves in an intermediate position, may send the assimilate in either or both directions. (Wardlaw 1965; Rowson and Hofstra, 1969). It has been recorded that in wheat and barley, the flag leaf and also second and third leaf to lesser extent (Lupton, 1961; Wardlaw, 1967; Rowson & Hofstra, 1969) and in corn, leaves above the ear (Allison and Watson, 1966; Hoyt and Bradfield, 1962) contribute its assimilate to the grain. Ample evidence indicate that not only the leaves but other plant parts such as fruit wall in peas (Bhardwaj and Raju, 1972), sepals in cotton (Patil and Mensink, 1972) and ear itself in barley (Thorne, 1965) also significantly contribute their assimi­ late to grain.