Thursday, 31 July 2008
Pelargonium x hortorum
Pelargonium x hortorum
FAMILY OF THE WEEK : GERANIACEAE
A family of 5 genera and 570 species and is cosmopolitan in distribution. In India 3 genera and 25 species occurring mostly in Himalayas: wild and cultivated variety.
Mostly herbs.The plants perennate by fleshy rhizomes or bulbous tubers.The stem is succulent and contains watery juice. The plants are glabrous or more commonly glandular pubescent.
The leaves are opposite or alternate, simple or often lobed or divided as in geranium. The stipules are usually present.
Inflorescence and flowers:
The commonest form of inflorescence is cymose.
The flowers are bracteate and usually bracteolate,complete,hermaphrodite,actinomorphic or zygomorphic,pentamerous and hypogynous.
The calyx is of five sepals which are free or rarely united, persistent, imbricate or rarely valvate.The corolla is also composed of five free petals alternating with sepals. The receptacle is scarcely expanded into a disc which has five glands. Usually there are ten stamens in two alternate whorls of five each.The anthers are diathecous introrse and dehiscing longitudinally.In Geranium a nectary is present at the base of each stamen of the inner whorl.
The gynoecium is usually five carpellary and syncarpous with a superior pentalocular ovary. The style is long with five stigmas.
Fruits and seeds:
Fruit is a schizocarpic.Often beaked and five lobed.
Pollination is by a variety of bees which visit the flowers for nectar.The seeds are scattered in all directions as the capsule opens by violence.
Wednesday, 23 July 2008
FAMILY OF THE WEEK : GENTIANACEAE
About 80 genera and 700 species worldwide.
Vegetative Characters : Herbs [shrubs or small trees], annual, biennial, or perennial. Stems ascending, erect, or twining. Leaves opposite, less often alternate or whorled, simple, base connate; stipules absent. Inflorescences simple or complex cymes, sometimes reduced to sessile clusters, often in a thyrse or 1-flowered. Flowers bisexual, rarely unisexual, 4 or 5 (or 6-8)[-12]-merous. Calyx tubular, obconic, campanulate, or rotate, lobes joined at least basally. Corolla tubular, obconic, salverform, funnelform, campanulate, or rotate, rarely with basal spurs; lobes overlapping to right or rarely valvate in bud; plicae (extensions of the corolla tube between the lobes) present or absent. Stamens inserted on corolla tube or occasionally at sinus between corolla lobes, alternate with lobes; anthers basifixed or dorsifixed, 2-locular. Nectaries absent or attached to ovary base or corolla. Ovary usually 1-locular at least apically, rarely 2-locular due to intrusion of a lamellate placenta into locular cavity. Fruit a 2-valved capsule, rarely a berry. Seeds many or rarely few, small; endosperm abundant [scant in saprophytic genera].
Pollination by insects.
Friday, 18 July 2008
FAMILY OF THE WEEK
PAPILIONACEAE(SUBFAMILY OF FABACEAE/LEGUMINOSAE)
This family is cosmopolitan in distribution but abundant in tropical and subtropical regions. In India 748 species occurring chiefly in peninsular India and the Himalayas.
They are predominantly herbs or herbaceous climbers; sometimes they are erect or climbing shrubs or trees. The climbers have climbing stems but often they climb with leaf tendrils.
The lateral roots of most plants have nodules which contain nitrogen fixing bacteria(Rhizobium)
The leaves are usually alternate simple,pinnately or digitately compound.In some genera terminal or other leaflets are modified into tendrils. Stipules are present and often stiplets are present. The leaf base is pulvinous.
The leaves of several genera perform sleep movements where the leaflets assume vertical position at night.
Inflorescence and flowers:
The Inflorescence is commonly axillary, leaf opposed or terminal raceme.Sometimes the flowers are arranged in panicles or dense axillary heads or they are solitary.
The flowers are often bracteate as well as bracteolate.They are complete,zygomorphic,hermaphrodite,pentamerous and hypogynous or perigynous.The calyx is composed of usually five sepals more or less united in a tube.The odd sepal is usually anterior.
The corolla is papilionaceous. The five petals are unequal and have a bilateral symmetry.The posterior(outermost) petal is called standard. The lateral pair of petals which are similar to each other and often clawed are called wings. The two anterior petals are united to form the keel which encloses the stamens and carpel.
The androecium is composed of ten stamens which are arranged in a single whorl in mature flower.The stamens are usually diadelphous. The filaments of nine are united into a long tube which encloses the ovary and the tenth posterior stamen remains free.Anthers are uniform but sometimes they are diamorphous. They are dithecous, introrse and dehisce longitudinally.
The gynoecium is monocarpellary with a superior or partly inferior unilocular ovary.The ovules are many to several on the ventral suture and the placentation is marginal.The style is simple and the stigma is capitate or terminal.
Fruits and seeds:
The fruit is a legume or pod dehiscing by one or both sutures into two valves or it is indehiscent.
Seeds are nonendospermic or with scanty endosperm and with a large curved embryo.
Pollination and dispersal:
Generally pollinated by bees or by self pollination.Nectar is present.
The seeds are usually dispersed by birds,animals or by human agency.
Examples and economic importance:
There is a large list of 100 genera and many species so only few are listed here.
The papilionaceae are of great economic importance and find a wide range of usefulness.
They provide important foodstuffs,valuable fodder,fatty oil,useful fibre,timber dyes,gums and several beautiful ornamentals.
The seeds of several species is rich source of starch and proteins and form an important part of our food.The widely used species include:
Pisum sativum L.(Garden pea)
Pisum arvense L.(Field pea)
Cicer arietinum L.(Chick pea,Gram)Tender seeds and shoots also used as vegetable.
Glycine max syn. Glycine soja(Soyabean)
Cajamus cajan syn. C indicus(Pigeon pea.Arhar)
Lens culinaris syn. L.aesculanta (Lentil,Masur)
Vigna mungo syn Phaseolus mungo((Black gram,Urd)
Vigna radiata L. syn Phaseolus radiatus(Green gram,Mug)
Vigna unguiculata syn sinensis(Cow pea)
Vigna aconitifolia syn Phaseolus aconitifolius (Moth)
Phaseolus sublobatus (Gora mung)
Phaseolus vulgaris(Kidney bean,French bean)
Phaseolus lunatus (Lma bean)
Phaseolus coccinius(Multiflora bean)
Dolichos biflorus L.(Horse gram,Kulat)
Lablab purpureus(Hyacinth bean,Sem)
Vicia faba(Field bean,Bankla)
Cyamopsis tetragonoloba syn.Cyamopsis psoralioides.(Cluster beans,Gawar)Seeds are source of Guar gum
Canavalia ensiformis DC (Jack bean)
Arachis hypogaea L. (Ground nut)
Pongamia pinnata syn.Pongamia labra(Pongam oil tree,Karanj)
Psophocarpus tetragonolobus DC (Goa bean)oil from seeds used for cooking and for soap making.
Crotolaria juncea(Sunhemp)Cultivated for making ropes and gunny bags.
Several members provide several pasture and hay plants such as Clovers(Trifolium alexandrium)
The following species provide timber:
Dalbergia latifolia(East Indian rosewood)
Pterocarpus marsupium (Bija)
Species cultivated for dyes
Pterocarpus santalinus(Red sandalwood,Lal chandan)
Crotolaria striata(Black dye)
Clitorea ternatea Flowers yield blue dye.
Butea monosperma syn.Butea frondosa (Dhak,Palas)Flowers yield fugitive orange red dye.The red juice of the plant is Bengal Kino used as astringent.
Astragalus gummifer is the source of important gum Tragacanth used as emulsifier in confectionary and cosmetic products.
Myoxalum balsamum:gum resins for medicines and perfumery.
Glycerrhiza glabra L.
Thursday, 10 July 2008
Family of the week:
EUPHORBIACEAE (Spurge Family)
Large and extremely variable family cosmopolitan in distribution except in arctic region but they are most abundant in tropical region. In India round 61 genera and 336 species mostly in tropical and subtropical Himalayas and in mountains of south India; while all over the world 7500 species.
The family shows great range in vegetative as well as floral forms. The plants are mostly shrubs or trees and rarely herbs sometimes succulent and cactus-like. The plants often contain a milky latex or sap in special laticiferous vessels.
The leaves are mostly alternate but may be opposite or whorled and they are simple, or compound, or sometimes highly reduced. Stipules are generally present but may be reduced to hairs, glands or spines. In cactus like habits the leaves fall off early and the photosynthesis is carried out by green stems.
Inflorescence and flowers:
The inflorescence is complex. The first branching is usually racemose and the subsequent branching is cymose.
A specialized type of miniature inflorescence called a cyathium occurs in about 1,500 species comprising the genera Euphorbia and Chamaesyce. The cyathium consists of a single naked pistillate flower surrounded by cymes of naked staminate flowers, each consisting of a single stamen.
These flowers are all enclosed in a cup-like involucre that typically is provided with peripheral nectaries and petaloid appendages such that the whole aggregation closely resembles a single flower. In other members of the family the flowers and inflorescences are more ordinary in appearance, with male and female flowers typically bearing a 5-merous calyx and corolla of distinct segments, although the corolla is sometimes absent. In these forms the androecium most commonly consists of 5, 10 or sometimes numerous distinct or monadelphous stamens. The gynoecium of female flowers consists of a single compound pistil of typically 3 carpels, an equal number of styles or primary style branches, and a superior ovary with typically 3 locules, each bearing 1 or 2 collateral, axile-apical pendulous ovules.
The flowers are monoecious;both male and female flowers are naked in Euphorbia whereas in Anthostema both have a tubular perianth. The flowers are unisexual, actinomorphic and hypogynous or rarely perigynous as in Bridellia.The flowers show considerable variation.
The number of stamens in male flowers ranges from one to numerousThe filaments are free or united in the form of a coloumn. A rudimentary ovary is often present in male flowers.An intrastaminal disc is present in flowers with many stamens.
The gynoecium is tricarpellary and syncarpous with a superior and trilocular ovary.The styles are three, often bipartite, free or more or less united. At the base of the ovary a nectiriferous disc is present which is annular or of separate glands.
Fruits and seeds:
Fruit is usually a three chambered schizocarpic capsule.Rarely a drupe or a berry.
Pollination is by insects.Seed dispersal is by explosion of capsule or through water or by birds aor animals.
Manihot esculanta (Cassava)
Manihot glaziovii(Manicoba rubber)
Hevea brasiliensis(Para rubber tree)
Ricinus communis(Castor bean,Erand)
Mallotus philippinensis(Kamela tree)
Jatropha curcas (Purging nut)
Hura crepitans(Sandbox tree)
Tuesday, 1 July 2008
Family of the week : DILLENIACEAE
Mostly tropical and subtropical.
Vegetative characters :Trees,shrubs or twiners (vines).The leaves are simple and alternate,entire or dentate,ususally with numerous promonent parallel lateral nerves; the stipules are absent or wing-like and adnate to the petiole, mostly deciduous.
Flowers :The flowers are actinomorphic and are bisexual or rarely unisexual. The perianth consists of 5 imbricate sepals and usually 5 imbricate petals. The androecium consists of numerous, distinct or fascicled stamens. The gynoecium comprises several distinct, simple pistils, each with a superior ovary and a single locule containing 1-many ovules.
The fruit is a follicle or is berrylike.