The common spotted orchid has an affinity for Southwest facing spaces. This is likely associated with the harmonizing effect the plant bestows upon the earth element, predominantly found in the Southwest direction. Please bear in mind that harmony in Feng Shui can be subjective and vary according to individual perspectives.

The Feng Shui compatibility of horse crippler appears to be promising, particularly in Northwest locations. The resilient nature of horse crippler could sync well with the symbolic energy of Northwest - a direction representing growth, resilience, and journey. This implies harmonious energy flow, providing a subtle balance amidst dynamic changes. But, remember, Feng Shui always depends on the specific contexts and personal destinies.

Rescuegrass can be considered moderately auspicious in the realm of Feng Shui. It best thrives when planted facing West, the direction associated with metal and the setting sun. This association aligns well with rescuegrass's resilience, although interpretation remains subjective.

The nodding thistle can be seen as a symbol of resilience and courage, each nodding head pushing upwards against adversity. In a southern position, it might inspire perseverance, tapping into the South's fiery and energetic qualities. However, given Feng Shui's subjective nature, its compatibility can change according to individual perspectives.

The saucer magnolia can be perceived as a dignified addition to any space, dependent on personal circumstances. If situated in an East-facing area, some believe it may invigorate the spirit of rejuvenation and growth, a key attribute associated with this cardinal direction. However, interpretations of Feng Shui vary distinctly, therefore, it's suggested to adapt according to one's instinct and comfort.

The firecracker flower is said to carry positive energy, making it a satisfactory choice for Feng Shui application. Especially when placed in the South, it encourages abundance and well-being due to its fiery hues, resonating well with the element of fire, a dominant aspect of southern Feng Shui. This, however, can be interpretive and depend on individual Feng Shui practices.

The scarlet morning glory has a moderate compatibility with Feng Shui principles. Its vibrant red color, emblematic of the Fire element, invigorates life energy or 'chi' within a space. Facing South, this plant can augment positive energy due to the alignment of the Fire element with the South direction, symbolically known for fame and recognition in Feng Shui. Yet, keep in mind that Feng Shui interpretations can vary considerably among practitioners and applications.

The fernleaf yarrow is an ardent enhancer of positive chi, particularly harmonious with a South facing direction. Its bright, golden flowers imbue an area with the fiery energy correlated with South, thus endorsing prosperity and recognition. However, like all elements in Feng Shui, achieving equilibrium requires thoughtful placement and complimentary companions.