CHAPTEE 11 'M OF LlTEEATUEfi Weeds are as old as agriculture itself. They form one of the most deleterious and expensive component in agriculture. It is of scientific interest that man has failed to control this persistent problem. On the other hand, he has seen them helplessly to create problems by their growing, spreading and disseminating seeds freely. About 30,000 weed species are widely distributed in the world; 1800 of which cause crop yield losses every year that make up about 9.7% of total crop production. Weed control has always been an important aspect of environmental protection. Over the past century, chemical herbicides have been effectively employed to control various weeds. However, they have caused many serious side-effects such as herbicide resistant weed populations, reduction of soil and water quality, and detrimental effects of herbicide residues on non-target organisms etc. (Te Beest and Templeton, 1985). Over the last decade, weed science research has shifted it's focus from herbicide discovery and its physiology to the study of weed biology and ecology. An overriding question is what makes a species a successful agricultural weed? This central question has been tackled fi-om a variety of angles, identifying and characterizing attributes contributing to weed success. Now a day's tools of physiology, molecular biology and genomic research are being utilized increasingly in these efforts. In India, weeds in general have remained neglected for many decades, even though they affect economy of agriculture. Literature reveals that, the work on weed Aristolochia bracteolata Lam. in country and outside as well has progressed along the following lines like weed survey, physiology, phytochemistry, pharmacognosy, ecology, pathology, and microbiology etc. Aristolochia is an important genus of order Piperales from the sub-family Aristolochoideae of family Aristolochiaceae and represented by 500 species (Kiew, 1999). Etymology The name Aristolochia (meaning the best delivery or birth) is thought to be of ancient Greek origin and reflects centuries of use in obstetrics aristos meaning "best" or, originally, "most fitting" and lochia which means "delivery." This is due to its original use to expel the placenta after childbirth. Other traditional uses include 12 treatment for snakebite, scorpion stings, fever, infection, diarrhea, and inflammation (Arlt et al, 2002, Jimenez - Ferrer et ai, 2005). Aristolochia hracteolata Lam. is commonly known as English - Wormkiller, bracteated Birthwort; Hindi- Gandan, Kidmari; Sanskrit - Dhomapatra, Gridhrani, Kitkaha, Kitari; Gujrati - Kidmari; Marathi - Gandhan, Gandhati; Kanada - Kattackirubangida; Malayalam - Aduthinnapala; Orya - Paniri; Tamil - Adulthinnapalai; Telgu - Gadugagudupa (Kirtikarc-/a/.,2005). Origin and phylogenetic information Aristolochiaceae family has been recently the subject of more attention because of the suggestions that these basal angiosperms are phylogenetically close to the divergence of monocots from dicots. Aristolochiaceae was traditionally placed in subclass Magnoliidae and thought to be related to woody members of the subclass Annonales; however, the first morphological cladistic analyses of basal angiosperms supported relationships of the family with other predominately herbaceous magnoliids (Piperales, Nymphaeales, Lactoridaceae) and the monocots. Subsequent phylogenetic studies supported relationships of Aristolochiaceae with more restricted set of paleoherbs (Lactoridaceae, Piperales, monocots), as well as Magnoliales, Laurales, and Chloranthaceae (Kelly and Gonzalez, 2003). Phylogeny of Aristolochiaceae based on parsimony, likelihood and Bayesian analyses of tm L- tm F sequences has been done to resolve position of Aristolochiaceae in Piperales (Neinhuis, 2005). This study addresses the overall generic relationships in Aristolochiaceae and its position in Piperales based on dense taxon sampling and sequence data from the plastid tmL-F region. All members of Aristolochiaceae have anatropous, bitegmic, crassinucellate, endostomic ovules with a few exceptions (Gonzalez, 2003). Razzak et a/.,(1992) studied pollination biology of Aristolochia bracteolata Lam. and reported that it is partially Protogynous. The flower exibits fly-trapping mechanism while pollen germination takes place within the dehisced anthers and on perianth parts. Geographic Distribution Aristolochia is the genus of shrubs, or rhizomatous perennial herbs, often twinning, mainly distributed throughout the tropics, but some species occur in warmer temperate regions also. The greatest diversity in Aristolochia species is found in Central and South America (USDA, 2010). In Malesian region 28 species have been 13 reported (Anonymous,!948). Aristolochia tagala Cham, has the largest area of distribution occurring from India and China, throughout South - East Asia to Austraha. (Kiew,1999). Species oi Aristolochia usually occurs scattered, often in primary forests, but some species are also found in secondary forest and scrub vegetation. The genus Aristolochia consists of species of herbaceous perennials, undershrubs or shrubs bearing essential oils and is widespread across tropical Asia, Africa and South America. Most European and tropical species of Aristolochia are believed to be pollinated by small flies attracted to the flowers by the foetid odours and purple- brown colour. Flies enter the flower when the stigmas are receptive and are trapped until after the anthers dehisce (Solereder, 1889). More than 30 Aristolochia species are native to the United States and occur in almost all states (USDA 2010). Indian Status About 15 species of Aristolochia occur in India of which three namely v4. bracteolata Lam., A. indica Linn, and A. tagala Cham, are usefiil in medicine (Santapau and Henry, 1973). The presence of Aristolochic acid, a nitrophenanthrene compound with tumour inhibiting properties, appears to be characteristic of the genus (NTP, 2008). Among these, Aristolochia bracteolata Lam. is most dominant in India and globally distributed in Tropical Africa, Arabia, Sri Lanka, and Pakistan. Within India, it occurs in northern and central India from Haryana to West Bengal and southwards to Tamil Nadu and Kerala. It is one of the dominant weed species of Maharashtra often found in dry regions (Murumkar, 1993). Plant Description Aristolochia bracteolata Lam. is a slender, decumbent, glaborous perennial with 30- 45 cm long. It is found to be distributed in hedges in the plains of Northern India from Haryana and Utter Pradesh and southwards to peninsular India up to Maharashtra and Andhra Pradesh. Leaves are varying variably in size and shape, reniform or broadly ovate, crenulate, undulate, long petioled. Flowers borne solitary, with perianth 2.2 - 5.0 cm long with subglobose base. Perianth tube cylindrical with trumpet shaped mouth and linear, dark purple coloured lip presence of glandular hairs within. Capsules are oblong-ellipsoid, 12 ribbed, glaborous. Seeds are deltoid with cordate base, rugose black on one side and whitish on the other, compressed (Wealth of India, 1982). 14 / Cultivation Several species of Aristolochia are grown as ornamentals chiefly on account of their remarkable, beautifiil and unusually shaped flowers. The plants bloom during summer as well as the monsoon, and bear a succession of highly coloured, mostly foetid flowers of variable size and shape. The individual flowers may last for a couple of days in sheltered positions. Although erroneously called 'Fly Catchers' i.e. Aristolochias are not insectivorous, but are insect pollinated plants i.e. entomophilous. The ornamental plant requires plenty of sun, protection from hot winds and mulch in the plains for overwintering. Garden soil mixed with leaf moulds and cowdung is desirable for cultivation o\ Aristolochias. Propagation is usually by seeds or by layering and cutting taken from well matured wood in early spring or at pruning time (Bor and Raizada, 1954). Germination Reports of germination studies are meagre. Only a few reports are available stating that Aristolochia seeds exhibit seed dormancy and highlighted various treatments for breaking seed dormancy. Maekawa, (2010) reported that presence of light and temperatures at 25*'C and 30 C favoured seed germination and normal seedling formation in A. esperranzae Whereas treatment of long period of cold stratifying temperatures was required for growth of underdeveloped embryos and seed germination in A.calfornica, A Macrophylla, A.tomentosa and A.manshurensis (Christopher, 2005). Anatomy Nair and Narayanan (1962) studied the Nodal and floral anatomy of Aristolochiaceae and reported that in A. bracteolata Lam. the vascular system of the axis, immediately below the node, consists of nine large, widely separated collateral vascular bundles. All of them enter the lamina to display the characteristic palmate venation. The leaves in A.bracteolata Lam. are cordate and palmately veined. The stomata are present only on the lower surface and are of the Ranunculaceous type (Metcalfe and Chalk, 1950). Foliar stomatal development in three species of Aristolochia has been studied by Philip (1983). 15 Conservation Status All species of Aristolochia are included in list A of Schedule I of the Export (Trade) Control Order, 1988 as the export of this plant and it's derivatives is banned. Collection of plant material from Reserved Forests is restricted under the Indian Forest Act. Low Risk-Least Concerned status has been assigned to the Aristolochia bracteolata Lam. in red list