Morphology of the Bur of Xanthium

Abstract

,I his communication reports on an anatonrical stucly of Sanlh%zitt~. slri~?t~arit~nr I.iri~i., \vilh respect LO the rcccp~acle, the b~~r , its spil~es, ailcl septum between the t\vo HOIVC~S of a fc~nale inHoresce11ce. T h e ali:~tomical cletails, prcsen~ecl herc, SLIP POI.^ i::1rr1s vie\\) (l915), \\.hich \\.as b;isctl cnrirely on ontogenical s t~~d i c s , ihat thc b i~r is a cotitin~~alion ol the receptacle, and that the spines it carries arc i~~oclilied floral bracrs. Observations'The female inflorescence of Xnqztl~iz~nz s t r~~m a r i z~m Linn. consists of only two flowers and is borne in the axil of a bract, \vhich should be considered as the inflorescence bract. I t is surrounded by a \vIlorl of involucral bracts, as described by Farr (1915), which do not, however, persist but fall oif a t the fruiting stage. Vascz~lar AnatomyThe inflorescence of Xanthium is attached to the axis by a large base, which is considered to be the receptacle. A transverse section passing through

Morpho-histogenic studies of the fruit wall ofArgemone mexicanaL. (papaveraceae)

“…The structural details of developing spine reveal that the epicarp and the mesocarp of developing fruit, together with pericarpic vascular bundles take part in the formation of spine. Thus the spine of A. mexicana shows developmental similarity with the spines of Xanthium (Trivedi and Sharma 1964), Datura (Dave et al 1980) and glochids of Urena lobata (Rao et al 1985) and of Triumfetta spp. (Dali and Dave 1999).…”

“…Like in Xanthium and Datura, the spines of Argemone mexicana also possess vascular strand, but it tapers towards the tip of the spine. Trivedi and Sharma (1964) equated the spine of Xanthium to a bract due to the presence of vascular traces in it, while Dave et al (1980) recognised the emergences present on Datura fruit as multicellular heterogeneous spiny projections. According to Roth (1977) emergences produce certain sculpturing on the fruit surface.…”