Background:

Tagetes contains about 55 species, its largest center of diversification is in Mexico with 35. Nearly 10 % of the species have cultural and economic importance. To date, anatomical studies are lacking in most of its species.

Question:

Are there foliar anatomical characters with diagnostic value that allow discriminating between the nine species of Tagetes studied?

Study species:

T. lacera, T. lemmonii, T. linifolia, T. lucida, T. lunulata, T. micrantha, T. parryi, T. stenophylla, T. zypaquirensis.

Study site and date:

Natural distribution areas in the Mexican Highlands, Trans-Mexican Volcanic Belt and the Genetics Experimental Field, Chapingo Autonomous University, Texcoco, State of Mexico, during 2017.

Methods:

Botanical specimens were collected. Leaves were fixed and subjected to conventional anatomical techniques, as clearing and embedding in paraffin for their observation and analysis.

Results:

Tagetes species develop entire and pinnatisect leaves, secondary venation pattern was eucamptodromous becoming reticulodromous distally and simple and festooned brochidodromous. The marginal ultimate venation was incomplete except for T. lunulata. Abundant and diverse trichomes, dorsiventral and isolateral mesophyll, collateral vascular bundles with sheath, and ducts in mesophyll and midvein were observed.

Conclusions:

The leaf architecture and anatomy of the studied species reveals common characters in Asteraceae. However, in Tagetes the type of trichomes, mesophyll, size of ducts, and sclerenchyma associated to vascular bundles are important.

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