Sertia

Name

Sertia

Rank

Genus

Authors (Name)

Golovneva L. B.  

Authors (Pub.)

Golovneva L. B. Nosova N. V.  

Publication

Al'b-senomanskaya flora Zapadnoj Sibiri [2012]

Authors (Book)

Golovneva L. B. Nosova N. V.  

Book

Al'b-senomanskaya flora Zapadnoj Sibiri

Page number

135

Year

2012

Parent Taxon

[Family] Platanaceae

Fossil Status

leaves

Type

Sertia kiensis

Diagnosis

Leaves simple, petiolate, 3—5-lobed, rhomboid or ovate in outline; frequently broader than longer; base widely cuneate or truncate; apex obtuse, rounded or acute; lobes elliptic or triangular, lower lobes bigger than upper ones; depth of lobe sinuses reaches ¹⁄₅—⅓ of the distance to the central vein, apices of lobe sinuses rounded. Margin dentate, teeth widely spaced, broadly triangular, with glands at the apices and rounded sinuses. Margin usually entire near the base and in the lobe sinuses. Venation palmate or pinnate-palmate, craspedodromous or semicraspedodromous. Basal veins diverge from central vein at the angle 50—60°, ending in lower lobes, usually straight, stout, with 6—8 basiscopic and 3—5 acroscopic branches. The lower basiscopic branches usually short, brochidodromous or semicraspedodromous, terminating by forming a series of loops along the margin. The middle branches are the longest and sometimes also branched. Below the basal veins 1 pair of thin and short infrabasal veins diverges from the central vein to join adjacent lower basiscopic branches. 3—4 pairs of secondary veins in the upper part of central vein diverge at the angle 40—50°. They are straight or slightly curved. Distance between basal and lower secondary veins signifi cantly bigger than distances between other secondary veins. In this space there are 2—3 intersecondary veins. Lower secondary veins sometimes terminate in upper lobes or small lobules. Tertiary veins percurrent, branching, sometimes reticulate. Higher-order venation orthogonal. Leaves hypostomatic. The epidermis comprises polygonal, isodiametric or elongated, irregular in shape ordinary cells, 24—40 μm in length and 13—20 μm in width. Anticlinal cell walls straight at adaxial epidermis and straight or undulate at abaxial epidermis. Periclinal cell wall with irregular wrinkles. The adaxial epidermis covered by numerous small compound trichome bases. The abscission scars about 10 μm in diameter, surrounded by thickened ring about 20—25 μm across, situated over the junction of several underlying specialized (smaller and more thickened) epidermal cells. The abaxial epidermis has stomata, compound trichome bases, numerous short simple trichomes, papilla-like trichomes and papillae. Stomata are broadly elliptic or subcircular, 17—25 μm in length with elliptical aperture and thickened stomatal ledges. Stomata brachyparacytic, paracytic, laterocytic, stephanocytic, stavrocytic or anomocytic, with 4—8 subsidary cells. Guard cells partly submerged under subsidiary cells; near their boundary usually there are crest-shaped folds. Simple trichomes 8—12 μm in diameter and 20—40 μm in length (up to 60 μm). Usually unicellular, rarely they comprise 2—3 cell; associated with 1—2 epidermal cell. On inner cuticle surface, the positions of papillous stalks of simple trichomes are marked by apertures. Papilla-like trichomes similar in morphogy, but shoter, 5—15 μm in length.