A study of Sparganium americanum (American bur-reed) composition to understand permeability of its leaf to chemical pesticides

Sparganium americanum Nutt, or American bur-reed, is an aquatic plant commonly found in water-retaining drainages. American bur-reed is capable of mitigating nitrogen and phosphorus from agricultural fields. The purpose of this study was to determine the composition of the leaf, with a particular emphasis on the cuticular waxes and the epidermis, and its ability to absorb pesticides. S. americanum leaves were collected in early and late summer of 2014. Transverse sections of S. americanum were stained with Sudan IV, Nile blue A, and also Phloroglucinol. The stained sections were studied with brightfield and fluorescence microscopy to estimate the structural and chemical nature of the leaf tissues cross sections. Extracts of leaves were studied in Vanillin and Nile blue A assays for a quantitative measurement of total lipids and leaf polarity. The average of total lipids in early summer was (1.45 +/- 0.73 mg/ml), and in late summer was (1.15 +/- 0.42 mg/ml). The average for polar extractable lipids in early summer was (0.91 +/- 0.85 mg/ml), and in late summer was (12.37 +/- 10.06 mg/ml). For nonpolar extractable lipids in early summer the mean was (66.93 +/- 25.31 mg/ml), and in late summer was (47.45 +/- 6.74 mg/ml). The leaves have higher nonpolar extractable lipid concentrations in both early and late summer than the corresponding polar lipid concentrations. Dermis preparations were assessed for the ability to absorb mixtures of pesticides (atrazine, malathion, cis-permethrin, and trans-permethrin) and analyzed with gas chromatography coupled with mass spectroscopy. The pesticide absorption results show that all pesticides pass through the dermis, and they did not bind to the leaves. The structure of S. americanum and the chemical nature of the leaves suggest this species does not have the capacity of absorbing these pesticides from agriculture fields.