In Feng Shui, blue ash carries a unique energy suitable for the Northwest facing direction. It's believed the tree's structural form and blue hues correlate well with the metal element, often associated with Northwest. This, however, might alter with different individual interpretations of Feng Shui.

The velvet tree-pear exhibits a propensity for harmonious balance when positioned in a Southeast-facing direction. This orientation enhances its growth, implying an amplification of prosperity and wealth energies, as per Feng Shui principles. However, this observation should be tailored to incorporate individual contextual factors, in line with the nuanced nature of Feng Shui interpretation.

The indian oak enjoys fair compatibility within Feng Shui. Practitioners suggest it radiates balance when positioned in the North direction of your space. This is because North correlates with the Water element, matching the indian oak's natural affinity for water, strengthening the energy flow in your environment. However, personal interpretation and adjustment are essential to attaining harmony.

The keijo maple is typically considered harmonious when aligned with the East, supposedly due to its association with growth and renewal - virtues inherent in this orientation. Nonetheless, the dynamics of Feng Shui are intricate and personal factors may influence the appropriate balance.

As an addition to any space, mexican giant hyssop embodies elements of growth, transformation, and the nurturing of vibrant energies, all subtly embedded within Feng Shui principles. Positioned in the South, mexican giant hyssop is said to invigorate the fire element of this direction, whilst its verdant foliage reflects a balanced array of natural life energies. The plant's compatibility with this direction, however, may vary and be interpreted differently according to individual Feng Shui practice.

The pill-headed sedge is a classic case of subtlety marrying strength. Its compact growth and rounded foliage portrays a sense of resilience and tenacity. This eases the negative energy fluxes in Southwest-facing arrangements. However, this idea toes the line of Feng Shui orthodoxy and is largely left to individual interpretation.

The canada lily aligns harmoniously with a southern facing direction, believed to channel the element of fire in Feng Shui doctrine. This harnesses energizing vibrations, which might interpretively enhance prosperity. Remember, individual perceptions of Feng Shui vary, making the actual manifestation subjective to individual interpretation.

The holy-flax is potentially harmonious with the Northeast direction, primarily due to its capacity to capture life-giving energy or 'Chi'. Legendary Feng Shui practitioners have mentioned its ability to sustain the positive flow of energy, despite its apparent resilience. Remember, Feng Shui is a complex art and responses may vary significantly.