Family: Poaceae

Pili is an indigenous clump-forming bunchgrass with a pleasing odor. Blades are about 12 inches tall, green in color with a hint of blue. Insignificant flowers form into a twisted spike with purple stigmas.  Seeds mature to a dark brown color with one end a long awn and the other end a sharp spike. Together they form a tangle of seeds set atop the grassy blades. 

Habitat & Uses

Pre-human contact, pili grew in open areas on the leeward sides from sea level to 2,300 feet elevation. Human disturbances have changed that landscape forever. Pili is fire-tolerant but not fire-adapted. Many invasive grasses are fire-adapted as they evolved where wildfire is common. Fire-adapted plants have traits that help them survive or even thrive in fire-prone environments, while fire-tolerant plants can withstand the heat and damage of a fire, but may not necessarily benefit from fire. Unfortunately, when fires sweep across a Hawaiʻi landscape, pili grass will die and be replaced by noxious weeds like fountain grass. 

Historically, pili was commonly used for hale thatching, floor coverings, and mattress stuffing. The pleasant aroma, brown color, and neat appearance of the grass blades made this plant a superior choice when constructing a home. A black dye could be concocted from the charcoal of the grass blades. Medicinally, pili and ash were mixed with coconut to treat ʻea (thrush) and pāʻaoʻao (childhood disease). Today, pili grass is a crucial component for the replanting of Kahoʻolawe as this species performs well in low fertility soils. 

Landscaping & Cultivation

Pili makes a magnificent accent or border planting. The grass grows tall enough to be a short hedge and the fibrous roots provide good erosion control.  Not a fussy plant, it flourishes in cultivation in both wet and dry areas, and it’s suitable for xeriscaping gardens. However, pili will be greener with more watering. Trim every year or so, especially after going to seed, to encourage new growth and a more robust appearance. Pili is an easy native to grow as it is generally pest free, requires little to no fertilizer, and thrives in the sun! 

The upright pili grass re-seeds itself, while the prostrate form needs replanting periodically. Propagation is from seeds or root division. When seeds are first collected from the plant they are dormant. You must store your seeds for about 12 months at room temp in a dry area. You should see 90% germination after seeds go through dormancy. Another method that may speed up this dormancy period is by planting seeds through watering in with diluted liquid smoke in water (at least 1% concentration). You should see about 50% germination success with this method. 

Name Origins

Pili means to ‘cling to’ in ʻŌlelo Hawaiʻi, a reference to the cork-screw-shaped seeds’ movement. After contact with soil, fur, feathers, clothing, or hair, the seeds naturally tunnel in. Likely, the seeds arrived to Hawai’i adhering to a bird’s feathers or muddy feet.  The genus Heteropogon is derived from Greek meaning ‘different beard’ as there are two kinds of floral spikelets on pili. The species name contortus refers to how the pili seeds contort when wet as they bury themselves into the soil. 

Plant Uses:

• Container plant
• Cultural significance
• Erosion control
• Fragrant
• Ornamental

Plant Dangers:

• No dangers