The ornamental plant known as the Asparagus Fern (Asparagus densiflorus or A. aethiopicus) is popular due to its delicate, feathery foliage. Despite its name, it is not a true fern but belongs to the Asparagaceae family, related to edible garden asparagus. A frequent concern for gardeners is whether local deer populations will treat it as a food source. Understanding the plant’s inherent defenses provides the clearest answer.
Asparagus Fern Palatability Ratings
The direct answer is that Asparagus Fern is generally categorized as a plant that is “rarely damaged” by deer. This classification denotes plants that browsing deer seldom select as a food source. They are not typically a primary or secondary component of a deer’s diet, suggesting a low palatability rating.
Deer may sample the plant out of curiosity or when investigating new growth. However, they quickly move on to more desirable forage after a single bite. The plant’s inherent characteristics ensure it remains low on the list of preferred foods, making it a reliable choice for landscapes where deer are present.
Characteristics That Deter Deer
The primary reasons deer avoid the Asparagus Fern are a combination of unappealing texture and chemical defense compounds. The foliage of Asparagus densiflorus consists of wiry, arching stems covered with needle-like structures called cladophylls. These tough, small, and sometimes sharp components do not offer the soft, succulent texture that deer seek.
The plant’s chemical defense is centered on the presence of steroidal glycosides, commonly known as saponins. These compounds are secondary metabolites that give the plant a bitter taste and can cause mild gastrointestinal distress if consumed in sufficient quantity. Saponins act as an effective antifeedant, signaling to the deer’s palate that the plant is not worth the energetic cost of eating. These deterrents are concentrated in the foliage and the small, red or black berries.
When Deer Ignore Their Preferences
The “rarely damaged” rating does not mean the plant is completely immune to browsing, as deer behavior is highly situational and adaptive. Deer may ignore their normal preferences when faced with extreme nutritional stress, such as during severe winter weather or prolonged drought. When preferred food sources are scarce, the deer’s need for calories and moisture can supersede their natural aversion to the fern’s taste and texture.
High population density can also pressure deer to consume plants they would usually pass by. If competition for favored forage is intense, the Asparagus Fern may be browsed simply because all other options have been exhausted. Young, tender growth may be slightly more vulnerable to browsing than mature, hardened stems. However, this consumption is typically localized and does not result in the wholesale destruction common with highly palatable species.