Cordifoliae

Mohapatra, Abhipsa & Janarthanam, M. K., 2020, Cystolith micromorphology in selected taxa of Ficus L. (Moraceae) in India and its taxonomic implications, Phytotaxa 436 (2), pp. 167-181 : 175

Section- Cordifoliae

Cordifoliae is one of the largest sections of Indian Ficus and represents the most taxonomically diverse group of plants. Berg (2004) divided this section into two subsections: ‟ Urostigma ” and Conosycea , based on morphological characters. A total of twelve species of this section have been studied, of which five belongs to ‟subsection Urostigma ” and seven to subsection Conosycea . Among the twelve species, six species have cystoliths on the adaxial layer, three on abaxial and three have cystoliths on both the layers.

In section Cordifoliae , among different cystolith characters studied, the type of sculpturing has been considered to be taxonomically the most significant one. The aculeate type is the most common type among the studied species, but further division of this pattern into three subtypes, i.e. broad, moderate and reduced aculeate along with the variations in length and width of cystolith appendages and the mode of stalk fixation provide further support for cystolith morphology to distinguish the species at sub-sectional level. For instance, F. arnottiana is morphologically quite similar to F. religiosa , both showing aculeate type, but can be distinguishable by the mode of stalk fixation and sub patterns of aculeate type, i.e. F. arnottiana with reduced aculeate and F. religiosa with moderate aculeate ( Figure 1H, I ). In addition, leaf anatomical characters such as number of epidermal layers, distribution of cystoliths either on adaxial or abaxial surface and their shape (spherical or ovoid) also support these distinctions ( Figure 3I, J ). The detailed description for each species of this section and the comparisons are discussed below subsection wise.

Figures

FIGURE 1. Sculpture patterns of cystoliths in Ficus species (SEM micrographs): A. F. pumila; with colliculate pattern (abaxial surface); B. F. exasperata; with verrucate pattern (adaxial surface); C. F. racemosa; with tuberculate pattern (abaxial surface); D. F. auriculata; with moderate aculeate pattern (abaxial surface); E. F. hispida; with tuberculate pattern (abaxial surface); F. F. callosa; with colliculate pattern (abaxial surface); G. F. amplissima; with broad aculeate pattern (adaxial surface); H. F. arnottiana; with reduced aculeate pattern (adaxial surface); I. F. religiosa; with moderate aculeate pattern (abaxial surface); J. F. tsjakela; with reduced aculeate pattern (abaxial surface); K. F. virens; with reduced aculeate pattern (abaxial surface); L. F. benghalensis; with moderate aculeate pattern (adaxial surface).

FIGURE 3. Transections of the leaf of Ficus species:A. F. pumila; spherical shaped cystolith (abaxial surface); B. F. exasperata; conical shaped cystolith develop only in the trichomal lithocyst (adaxial surface); C. F. tinctoria subsp. gibbosa; cystolith are found absent on both the epidermal surfaces; D. F. racemosa; spherical shaped cystolith (abaxial surface); E. F. auriculata; spherical shaped cystolith (abaxial surface); F. F. hispida; spherical shaped cystolith (abaxial surface); G. F. callosa; ovoid shaped cystolith (abaxial surface); H. F. amplissima; ovoid shaped cystolith (adaxial surface); I. F. arnottiana; spherical shaped cystolith (adaxial surface); J. F. religiosa; ovoid shaped cystolith (abaxial surface); K. F. tsjakela; ovoid shaped cystolith (abaxial surface); L. F. virens; spherical shaped cystolith (abaxial surface). Scale bars are 50 µm.