Ere russet fields their green resume,
 Sweet flower, I love, in forest bare,
To meet thee, when thy faint perfume
Alone is in the virgin air.
Of all her train, the hands of Spring
 First plant thee in the watery mould,
And I have seen thee blossoming
 Beside the snow-bank's edges cold.
Thy parent sun, who bade thee view
 Pale skies, and chilling moisture sip,
Has bathed thee in his own bright hue,
 And streaked with jet thy glowing lip.
Yet slight thy form, and low thy seat,
 And earthward bent thy gentle eye,
Unapt the passing view to meet
 When loftier flowers are flaunting nigh.
Oft, in the sunless April day,
Another reference to the violet being modest as mentioned before. Modest in a sense of sitting low and bending gently.
The Yellow Violet