Characteristic Trichomes and Indumentum Specialization in African and European Parasitic Scrophulariaceae

Abstract

Trichomes and their distribution patterns have been observed in the aerial parts of plants of the genera Striga, Buchnera, Rhamphicarpa, Euphrasia, Melampyrum and Rhinanthus, using both light (LM) and scanning electron microscopy (SEM). All trichomes belong to the multicellular, uniseriate category and can be classified as glandular and nonglandular types. On nearly all organs, the two types can be observed side by side. Apart from a large group of ubiquitous trichomes, some characteristic trichome types are reported; they are restricted either to chlorophyllous organs (foliage leaves, bracts, calyx and stem) or to the corolla, In some nonglandular trichomes minerai deposits have been found. Other morphological and anatomical trichome features are discussed with regard to their possible function.

The Genus Striga (Scrophulariaceae) in Africa

“…The vestiture of S. klingii is unique, as noted by Neumann et al (1996) and Musselman (unpublished), with curved hairs that have very broad shield-like bases. Perennial, to 60 cm tall, stiffly erect, unbranched or with 2 to 3 branches from base, pubescent, stem square, furrowed.…”

“…12,13). Striga macrantha has unique glandular trichomes composed of a 10-16-celled glandular head (Neumann et al, 1996) Annual, to 45 cm tall, erect, unbranched or with 2 to 3 branches from middle, covered with dense, hispid hairs, stem obtusely square. Leaves 15-30 X 10 mm, alternate, pinnatifid with linear segments, shorter than internodes.…”

“…Many species have scabrous leaf and stem surfaces at maturity. The most common trichome types include: glandular trichomes; stiff hairs (hispid); long soft hairs (pubescent or pilose); long stiff hairs (ciliate) (Neumann et al, 1996). 4.…”

Ultrastructure of hydathode trichomes of hemiparasitic Rhinanthus alectorolophus and Odontites vernus: how important is their role in physiology and evolution of parasitism in Orobanchaceae?

“…2010). Moreover, very similar trichomes occur on leaves of various Pedicularis species (Fedorowicz 1915; Kaplan & İnceoğlu 2003) and Neumann et al. (1998) reported frequent occurrence of glandular trichomes in various species of the Orobanchaceae (unfortunately without listing them) including the intensively studied genus Striga and related Buchnera .…”

“…(1998) reported frequent occurrence of glandular trichomes in various species of the Orobanchaceae (unfortunately without listing them) including the intensively studied genus Striga and related Buchnera . Although Neumann et al. (1998) classified these trichomes as the same as the stalked hydathode trichomes in the Rhinanthoids (and termed them ‘ubiquitous glandular trichomes’), their anatomy appears to be slightly different (based on a few light and SEM micrographs provided in the study).…”