Abstract Detail

Development and Structure

Cerros-Tlatilpa, Rosa [1], Ceja-Romero, Jacqueline [2], Mendoza-Ruiz, Aniceto [3].

Leaf anatomy of Phthirusa inorna (B.L. Rob. & Greenm.) Kuij and P. conspicua (Benth.) Eichler(Loranthaceae) from Mexico.

Phthirusa Mart. is one of the six genera of Loranthaceae that occur in Mexico together with Cladocolea Tiegh, Oryctanthus Eichl., Passovia H. Karst., Psittacanthus Mart., and Struthanthus Mart. According to Kuijt (2011), Phthirusa comprises seven species in the tropics and subtropics in the New World. Only Phthirusa inconspicua and Ph. inorna are restricted to Mexico. The genus comprises small hemiparasitic shrubs, with terete or compressed stems; small leaves, alternate or decussate; flowers are sessile, tetramerous, single in leaf axils, hermaphrodite; fruits a small berry red or black. Although leaf anatomy has proven very important in the plant taxonomy, limited studies are known in American Loranthaceae. In this study Mexican species of Phthirusa are surveyed and anatomical characters are described. Leaf samples and herbarium vouchers were collected in Guerrero, Jalisco, Oaxaca, Michoacán, Morelos and Puebla. Mature leaves were selected, and 5 mm long segments from the middle portion of the blade were fixed in FPA, following dehydration via an ethanol series, samples were infiltrated and embedded. Transverse sections of 10 µm thickness were made and stained according to Johansen’s method (1940). Leaf blade anatomy of Mexican Phthirusa species in transverse section range from flat to wide V-shaped. Epidermis is uniseriate, glabrous with rectangular cells, a smooth cuticle, ridged only on the margins. Stomata are distributed both on the adaxial and abaxial epidermis. Mesophyll is isobilateral. Palisade parenchyma consist of 2-4 layers both lower and upper surface of the leaf with abundant phenolic compounds. Spongy parenchyma occurs through the center of the leaf with copious calcium oxalate druses and prismatic crystals. Midrib is indistinct with single vascular bundle (VB) and collenchyma girders are adaxial. All VB are collateral in a single central row. Only P. conspicuahas cristarque cells and few sclereids are found scattered in the mesophyll. In addition, phenolic compounds are equally abundant on palisade parenchyma with a gradual decrease toward the spongy parenchyma. Plant under stress accumulate crystals and secondary metabolites to resist pathogens and herbivores (Gershenzon 1984). Both Phthirusa species are distributed mainly in tropical deciduous forest and have deciduous and delicate leaves. Further sampling including the seven species will contribute to understand the anatomical variation within this genus.

1 - Universidad Autonoma del Estado de Morelos, Facultad de Ciencias Biológicas, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, Mor, 62209, Mexico
2 - Universidad Autónoma Metropolitana, Área de Botánica Estructural y Sistemática Vegetal, Departamento de Biología, Av. San Rafael Atlixco186, , Iztapalapa, Ciudad de México, 09340 , Mexico
3 - Universidad Autónoma Metropolitana, Área de Botánica Estructural y Sistemática Vegetal, Departamento de Biología, Av. San Rafael Atlixco186, , Colonia Vicentina, Iztapalapa, Ciudad de México, 09340, Mexico

Keywords:
Mistletoes
leaf anatomy
Hemiparasites
Loranthaceae.

Presentation Type: Poster
Session: P1, Development and Structure Posters
Location: Virtual/Virtual
Date: Monday, July 19th, 2021
Time: 5:00 PM(EDT)
Number: P1DS012
Abstract ID:887
Candidate for Awards:None