Palynological Studies on Ten Species of Angiosperms from Nepal

Palynological studies on ten species of angiosperms family namely Hibiscus rosasinensis L.(Malvaceae), Lilium candidum L. (Liliaceae), Petunia axillaris (Lam.) B.S.P.(Solanaceae) and seven species from family asteraceae namely Artemisia indica Willd., Aster ageratoides Kitam., Calendula offcinalis L., Cerpis japonica L. (Benth.), Sonchus asper (L.) Hill, Tagetus patula L., and Taraxicum officinale F.H.Wigg. was carried out. Result obtained from this investigation showed that pollen shape is spheroidal in Artemisia indica, Aster ageratoides, Calendula offcinalis, Hibiscus rosasinensis and P. axillaris; elliptical in L. candidum, hexagonal in S. asper and pentagonal in T. officinale; tricolpater in C.japonica. Pollen aperture is porate in all except in L.candidum where it is elliptic. Pollen wall is echinate in H.rosa-sinensis, A.ageratoides, T. patula; spinulate in P. axillaries, T. officinale, S. asper, C. japonica, C. officinalis and T. officinale and smooth in L. candidum. The general appearance of the pollen grain is circular in P. axillaries but longer than wide in L.candidum. The circular, echinate, large and triporate pollens seem to be primitive ones and spharoidal, hexaporate features have been regarded as comparatively advanced ones. Polyporate pollens are considered to be secondarily derived. The nature of the pollen grain in these species could be evolutionary significance. The similarities in structure of the pollen grain showed the interspecies relationships among the species and that’s why put in same family while the differences in structures showed reasons for them to exist as distinct species. Only one species namely L.candidum from monocot family (Liliaceae) included in this study.


Introduction
Ten species of angiospermic plants were selected for Palynological studies.There characteristics were described below.

Artemisia indica Willd.
The plant is commonly known as wormwood and belongs to tribe Anthemideae of the family asteraceae.It is perennial herbs or shrubs, 80-150 cm tall and glabrescent.Leaves short petiolate or subsessile, upper surface of blade grey or yellowish, tomentose or glabrescent, lower surface densely P. Karna (Mallick) (2017)   This paper can be downloaded online at http://ijasbt.org&http://nepjol.info/index.php/IJASBTageratoides, commonly known as the Japanese Aster.Leaves hairy, margin serrate.Flowers white capitulums.

Calendula officinalis L.
This plant is belongs to the tribe Calenduleae of the family Asteraceae.The plant is a short living.The plant is aromatic and erect annual herb.The plant is growing up to 80 cm tall and branched stem.The stem is angular, glandular and hairy.The leaves 2.5-7.5 cm, oblong, lanceolate and hairy on both sides, entire margins.The inflorescence is yellow comprising a thick capitulum.

Crepis japonica L. (Benth)
The plant is commonly known as hawksbeard and belongs to tribe Cichorieae of the family asteraceae.The species is an perennial herbs and with milky latex.Leaves mostly rosulate, glabrous.Capitula ligulate, many-flowered, solitary, terminal or in lax corymbs.Florets bisexual, fertile, corolla yellow, tube shorter than lamina, oblong, 5-toothed.

Hibiscus rosa-sinensis L.
It is commonly known as china rose or shoe flower and belongs to Malvaceae family.The taxa Hibiscus rosasinensis is a bushy and evergreen shrubs or small tree growing 2.5-5 m tall and 1.5-3 m wide and with solitary red flower and glossy leaves.The plant flowers in summer and autumn.

Lilium candidum L.
It is commonly called as white lily flower, belongs to monocot family liliaceae.It is a perennial plant growing up to 60-150cm in height.It is a bulb species with large scaly white bulb, 1m.tall stalks and linear leaves with dented margins.Plant is strongly aromatic.

Petunia axillaris (Lam.) B.S.P.
Petunia is an annual herbaceous plant in the family Solanaceae and closely related to tobacco, tomatoes, deadly nightshades, potatoes and chili peppers in the same family, Solanaceae.The plants are hebaceous, generally hairy, and the flowers are funnel-shaped, with petals joined together.

Sonchus asper L. (Hill)
This taxa is belongs to the tribe Cichorieae of the family asteraceae.The plant is annual, erect.Root stalky, vertical.Stem straight, branchy, and glabrous below, 70-80 cm in height.Leaves integral or emarginate-incised, with sharp incisions and prickly marginal denticles, elongate-ovoid, rigid, pointed, less often blunt, radical and lower leaves are narrowed toward winged petiole; middle and upper leaves sessile, with wide amplexicaul base.Inflorescences are calathidia, aggregated at the end of stalk and branches in small umbrella-shaped corymbs.Flower stalks and involucre are covered with dark glandular hairs, sometimes the hairs are absent at the upper parts of flower stalk.

Tagetus patula L.
This plant is belongs to the tribe Helineae of the family asteraceae.The plant is annual herbs, usually erect, glabrous, and strongly aromatic.Stems simple or diffusely branched.Leaves opposite or alternate, sessile, base expanded with several, narrow, linear segments, pinnate or rarely simple, lobes lanceolate to narrowly elliptic, margins sharply serrate.The leaves coated with oily glands that produce a pungent scent.Capitula usually radiate, fewflowered, solitary on long peduncles or corymbosely arranged.

Taraxacum officinale F.H.Wigg.
This taxa also belongs to the tribe Cichorieae of the family asteraceae.The plant is herbaceous perennial with a rosette of jagged, irregularly lobed leaves produced from a long, thick, fleshy taproot that can descend more than 1 m.The leaves may be nearly smooth-margined, saw-toothed, or deeply cut.The single flowering stalks, sometimes over 50 cm tall, and bears a head of tiny yellow flowers.The flowering stalk is hollow and elongates with age.
The main objective of this study is to examine the pollen morphology of ten species of angiosperms.Palynology is the study of plant pollen, spores and certain microscopic plankton organisms, collectively termed palynomorphs in both living and fossil form.The variation in shape, aperture, polar unit, symmetry and difference in wall sculpture of pollen grains has been used by many authors in the delimitation of various taxa (Mbagwu et al.,2009).Nyananyo (1985) on pollen morphology of Talineae showed that palynology provides useful data for the intrageneric classification of the large genera.Nyananyo (1990); Mbagwu and Edeoga (2006) have utilized pollen attributes to establish probable evidence of relationships among certain groups of flowering plants in Nigeria.

Materials and Methods
Mature buds of living plants specimens were collected from central parts of Nepal.Then all buds of each plants stained in solution of 1% aceto-carmine separately and heated it for few seconds over spirit lamp and left it for one hour for proper staining.A single mature anthers were dissected from the buds and teased with a needle in a thin film of 1 % aceto-carmine on a glass slide (Mallick, 2015).After removing the debris the cover slip was placed over it.Excess stain was drained off with blotting paper and observed under 10x eye piece and 100x objective magnification of oil immersion compound microscope.Photomicrographs were taken with the help of digital camera of 12.1 megapixel using 10x eye pieces and 100x objective of compound microscope.Later on photographs were enlarged to suitable sizes.This study was conducted in Central Department Botany of Tribhuvan University as well as Botany Department of Tri-Chandra Multiple Campus, Kathmandu.The methodology was used according to Levan et al. (1965).(2005).Polyporate pollen grains are considered to be secondarily derived one (Hoot, 1991).In most of the studied taxa are triporate, echinate exine wall.Palynomorphology of the taxa has played an important role in the formulation of phylogenitic groups (Manandhar, 2005).Vishnue-Mitre and Sharma (1962) have reported more than three types of pollens in leguminous plants on the basis of pollen apertures and exine patterns.Reddy (1992) have reported palynological studies of 20 species of genus Indigofera.
From the present palynological studies it is concluded that the nature of the pollen grain in these species could be evolutionary significance and they are useful in classification of family at specific and generic levels.

Table 2 :
Pollen morphology of the another five species of angiosperms studied 2: a. L. candidum with elliptical pollen aperture and smooth pollen wall; b.P. axillaris with polyporate aperture and spinule pollen wall, c. S. asper with hexaporate echinate pollen exine; d.T. patula with triporate aperture aperture and echinate pollen; e. T. officinale with pentaporate aperture and echinate pollen wall and exine Tricolpate and pentacolpate with variable number of pores (triporate and polyporate) found by Vaidhya (2005) in family Ranunculaceae.Tricolpate and triporate pollens are considered to be most primitive pollen types Vaidhya