Bhashya
ये त्वन्ये अनुशयिभ्यश्चन्द्रमण्डलमनारुह्य इहैव पापकर्म-भिर्घोरैर्व्रीहियवादिभावं प्रतिपद्यन्ते, पुनर्मनुष्यादिभावम्,तेषां नानुशयिनामिव दुर्निष्प्रपतरम् ।कस्मात् ? कर्मणा हितैर्व्रीहियवादिदेह उपात्त इति तदुपभोगनिमित्तक्षये व्रीह्यादि-स्तम्बदेहविनाशे यथाकर्माज्जितं देहान्तरं नवं नवं जलूकाव-
In plain words
There is another class of souls who never ascend to the moon. Because of their dark and terrible deeds, they are reborn directly here on earth as plants like rice and barley, and only later return to human form. For these souls, escaping the plant state is not nearly as difficult as it is for the virtuous souls who are merely descending through the rain. Why? Because for these sinful souls, the plant body is an actual punishment-birth earned by their own karma. Once the karmic debt of that specific suffering is paid and the stalk of rice is cut down, they immediately move on to a fresh body earned by their remaining deeds—gliding smoothly from one form to the next, just like a leech stepping from one leaf to another.
Close to the Sanskrit
But those others, different from the souls with residual karma, who do not ascend to the orb of the moon, and who, right here on earth, due to their terrible evil deeds, attain the state of being rice, barley, etc., and subsequently the state of being human, etc.—for them, it is not so exceedingly difficult to escape as it is for the souls with residual karma. Why? Because indeed, by their own karma, the body of rice, barley, etc., was acquired by them as an actual birth; therefore, when the karmic cause for that experience is exhausted, and upon the destruction of the body of the clump of rice, etc., they enter a new, fresh body earned in accordance with their past deeds, just like a leech.