First, let's analyze the structure of the sonnet "The Lotus" by female Indian poet Toru Dutt. It is fourteen lines written as an octave (or octet) and a sestet: eight related lines followed by six related lines. There is a turn in the logical progression of the subject at the line 9 volta. Here, the general discussion between "flower factions" in Psyche's garden turns to direct dialogue between Love and Flora: "'Give me a flower delicious as the rose ....'" The sestet resolution to the problem between Love and Flora is presented as a surprise twist when Flora offers the lotus:
And Flora gave the lotus, "rose-red" dyed.
And "lily-white,"--the queenliest flower that blows.
The rhyme scheme is abbaacca dedeed. There is no ending couplet though there is an ee couplet in the sestet.
Petrarchan structure is similar though there are some variations. Petrarchan sonnets are fourteen lines written in an octave and sestet. There is a turn in the logic of the subject at the line 9 volta. Petrachan resolution usually presents a paradoxical twist. Petrarchan rhyme scheme for the octave is an invariable abbaabba. The sestet may be one of many combinations of cde endings including cddcdc cdeced cdcedc.
"The Lotus" is like Petrarchan sonnets in that it has the octave-sestet structure. It also has the turn in logic at the volta and paradoxical twist resolution. The rhyme scheme of the octave varies from the Petrarchan abbaabba (with three couplets) scheme. This variation creates a deviation in the sestet rhyme scheme. Since /c/ is already in the octave, the sestet must be structured around /d/: dedeed.
According to University of Maryland's "Romantic Circles," this abbaacca rhyme scheme was developed by William Wordsworth. Since Dutt (March 4, 1856) was born close to one hundred after Wordsworth (April 7, 1770), and since she attended lectures for women at Cambridge in England, it is probable that she intentionally borrowed Wordworth's variation for her own poetry. In summary, Dutt's sonnet has many features that adhere to Petrarchan sonnet form though she opts for the Wordsworthian rhyme scheme thus varying and deviating from the Petrarchan scheme.