In terms of Feng Shui, the mexican hens plant aligns harmoniously with a West-facing direction. This is because the direction signifies metal element, which complements this succulent's tenacity and ability to thrive in tough conditions, symbolizing Metal's characteristics. This, however, should be considered a general guideline rather than an absolute rule, as Feng Shui interpretations can greatly vary due to different perspectives and contexts.

False buck's beard is considered a harmonious plant in Feng Shui, known for creating a positive energy flow. Its lush foliage and delicate blossoms promote a sense of tranquility and balance. When facing North, false buck's beard is believed to enhance career luck and networking opportunities, perfect for those seeking professional growth and success in their workspace.

Onions (Allium cepa), or onion, might exhibit intriguing influences when in alignment with Feng Shui principles. Their vigorous growth could be harmonizing with the robust and independent energy of the Northwest direction. However, caution is advised since their potent odor might contradict the serene ambiance we associate with Feng Shui.

The downy oak bears a semblance to the steady yet adaptable energy of the Earth element in Feng Shui. Naturally harmonising with an East-facing orientation, the plant could be seen accentuating health due to the association of East with family and health. Please interpret with thoughtful discretion considering variables in your environment.

The karo is suitably compatible with Feng Shui principles, offering a tangible balance of Yin and Yang energies. Ideally placed in the east-facing areas of your home, it can harness and enhance the essential life force Chi. This is mainly due to the plant's resilient nature, which epitomizes the Wood element, traditionally associated with the Eastern direction.

The wax mallow plant illuminates a subtle ambiance of harmony and prosperity, enhancing the Feng Shui energy flow in one's living space. It fits ideally facing North, as water element resides there and this plant thrives well in areas with higher humidity, simulating a harmonious water influence. However, the interpretation of Feng Shui principles can vary, so it's essential to integrate them according to personal comfort.

In Feng Shui, the groundsel bush has a questionable compatibility. Its resonant energies may combine elegantly with the nurturing character of the Northeast direction. Its vibrant growth symbolizes enduring vitality, which is valued in Feng Shui, though results may vary depending on individual circumstances.

The yellow archangel plant carries a nuanced balance in Feng Shui, deemed to be both vibrant and calming. When positioned in the West, it can potentially enhance creativity and inspire joy due to its bright yellow flowers. However, as with any Feng Shui application, the impact of yellow archangel might differ based on individual circumstances and personal Chi flow.