JSFiddle - React, Tailwind, and code Playground

HTML

<fieldset id="timesheet-rows">
    <legend>Add Trees</legend>

    <div class="timesheet-row">

        <label>Species:
            <select name="species[]" required>
                <option value="Avocado" />Avocado</option>
                                                                                <option value="Lemon" />Lemon</option>
                                                                                
                                <option value="Mango" />Mango</option>
                                                                                               <option value="Stinkwood" />Stinkwood</option>
            </select>
        </label>

        <label>Number of Trees:
            <input type="number" step="1" name="hours[]" width="5" placeholder="0" required />
        </label>

    </div>

    <input type="button" id="add-row" name="add-row" value="Add Species" />
</fieldset>

JavaScript

jQuery(function($) {
  var $button = $('#add-row'),
    $row = $('.timesheet-row').clone();

  $button.click(function() {
    $row.clone().insertBefore($button);
  });
});