Japanese sweet flag's compatibility with North-facing direction in Feng Shui is seen as auspicious due to its noted resilience and year-round greenery, representing steady growth and prosperity. However, its appropriateness may vary based on individual circumstances and orientations, underscoring the context-specific and interpretive variedness of Feng Shui wisdom.

Common Speedwell holds a special place in Feng Shui as it's believed to balance Yin and Yang energies. Facing Northeast signifies growth and knowledge, and common Speedwell, with its gentle, calming influences, is considered enhancing for this direction. It is however critical to remember that placement should depend upon individual spatial layouts and energy flows. The true harmony lies in interpreting and adapting Feng Shui to personal needs.

The large-lipped encyclia is fairly compatible with Feng Shui principles. Particularly when placed in a North-facing direction, this plant can potentially induce a sense of calm and serenity, beneficial in nurturing introspection, due to its robust green foliage symbolizing growth and renewal. However, like with all Feng Shui practices, the effect is highly subjective and varies greatly among individuals.

The saguaro, in the realm of Feng Shui, is considered a commanding embodiment of steadfastness and longevity, mirroring the principles of Earth and Metal. This makes its compatibility with the Northeast, an Earth element direction, reasonably harmonious. However, due to the unique nature of Feng Shui, individual experiences could differ, thus making its efficacy subjective.

Gynura divaricata is believed to have a harmonious relationship with North-facing environments. This is theorized due to its innate affinity for cool, shaded spaces reflecting water element in Feng Shui, common in the Northern areas of a dwelling. As with all Feng Shui concepts, varying interpretations may exist.

The mountain house-leek plant carries a strong yet serene energy, much like the mountains it hails from. It upholds a harmonious compatibility with the Northeast direction, primarily due to its robust vitality and resilience, naturally aligning with the elemental essence of Earth, predominant in this sector. This connection, however, is always open to individual interpretation and personal experience.

The white lupine inherits a splendid characteristic that embodies both receptivity and vitality, hinting at a delightful correlation with northern orientation. Its stark white blooms resonate with elements of the water direction, subtly encouraging a harmonious energy flow. However, one's personal perception holds the key to actualizing this potential compatibility.

Angelonia could potentially harmonize with a Northeast-facing space, considering its potential symbolic tie to growth and fortune. However, its inclusion should be thoughtful due to Feng Shui's multifaceted principles and personal interpretations.