Cenchrus purpureus (Napier or Elephant Grass)

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Cenchrus purpureus is a perennial grass that grows up to 4m tall. The stem is erect, soft, and heavily branched at the top. 

It is easily identifiable by its thick clumps, which form from the basal offshoots, and its long green leaf blades.

Cenchrus Purpureus Scientific Classification

  • Domain: Eukaryota
  • Kingdom: Plantae
  • Phylum: Spermatophyta
  • Subphylum: Angiospermae
  • Class: Monocotyledonae
  • Order: Cyperales
  • Family: Poaceae
  • Genus: Cenchrus
  • Species: Cenchrus purpureus
  • Varieties: Bana, French Cameroon, Kakamega I, II, and II, Uganda hairless, and Clone 13
  • Common Names: Cane grass, Merker grass, Uganda grass, Bana grass, Barner grass, Napier fodder, napiergrass

Nativity and Distribution

Napier Grass is native to Tropical Africa. It can be found in:

  • Kenya
  • Tanzania
  • Uganda
  • Angola
  • Benin
  • Ethiopia
  • Ghana
  • Nigeria
  • Malawi
  • Zimbabwe

Physical Characteristics

Elephant grass has long leaf blades about 100-120 cm long
Elephant grass has long leaf blades about 100-120 cm long. Image: Facebook/supernepiark
  • Leaves: Flat linear leaves with a prominent whitish midrib.
  • Stems: Strong and erect. It can grow up to 4m.
  • Flowers: Yellow-brown to purplish spike bristles 15-20 cm long.
  • Roots: Fibrous root system.

Cenchrus Purpureus is a perennial grass with an erect habit to 4m in height. It is easily recognized by its robust clumps (up to 1m) across from the basal offshoots and long green leaf blades.

Stems are upright, relatively robust, about 3 cm thick, and hairy. The leaves are alternately arranged with leaf blades 100-120 cm long that emerge from a leaf sheath enclosed in the stem. 

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They have a prominent white midrib, rough margins, and a pointed apex. There are dense hairs about 1.5-5mm long where the leaf sheath meets the leaf blade. 

The leaf blade varies in size from 1-5 x 100-120 cm. 

The flower heads are about 2 cm wide and 20-30 cm long and are arranged in a dense spike-like panicle. They can vary in color from purplish to silvery. The spikelets, 4-6mm, are surrounded by 2cm long bristles that contribute to the fluffy texture of the flowerhead. 

The elephant grass seeds are small, elongated, and yellow-brown in color. 

Reproduction, Dispersal, & Life Cycle

  • Life Cycle: Perennial 
  • Seeds: Produces few viable seeds
  • Climate: Grows well in tropical areas 
  • Dispersal: Wind, animals, and agricultural activities

Cenchrus purpureus behaves as a perennial weed. It has an inconsistent seed production system with few to no seeds each growing season.

Napier grass reproduces through its rhizomes (underground stems) to grow new shoots. As a valuable forage grass, it is also reproduced by planting stem fragments in the soil, allowing it to develop roots and new offshoots.

The cuttings are made from stems with at least three nodes and planted 10 cm apart in rows about 30 cm apart. This allows for fast propagation and establishment of new plants.

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The few seeds produced are dispersed by wind, animals, and vehicles. They are also spread as part of agricultural produce like fodder. 

Similar Plants

  • Cenchrus polystachios (Mission Grass)
  • Cenchrus macrourus (African Feather Grass)
  • Cenchrus pedicellatus (Deenanath Grass)
  • Cenchrus alopecuroides (Swamp Foxtail)

Uses

Napier grass is largely used as fodder for livestock
Napier grass is largely used as fodder for livestock. Image: Feedipedia/ILRI
  1. Napier grass is a valuable forage, hay, and silage crop for feeding livestock and other ruminants.
  2. It is used to stabilize soil and prevent erosion.
  3. It is used to improve soil fertility. 
  4. It’s an important raw material for biofuel production due to its high biomass yield.
  5. It is used as a windbreaker in horticultural farms and orchards. 
  6. It is used as mulch for moisture retention and weed suppression. 
  7. The grass is used as reinforcement for mud huts.
  8. The leaves and stems are used to create diuretic, laxative, and analgesic remedies in Africa.
  9. It is used to mark boundaries between properties. 
  10. When used with molasses grass, it can be a valuable biological agent to control maize stemborer moth.

Impact on Farms and Environment

C. purpureus is considered an invasive weed in many countries in the world. Its aggressive and rapid growth can colonize new areas quickly and outcompete native plants. 

The dense thickets also pose a flood risk in flood-control systems by reducing water flow and blocking canals. 

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However, it can offer numerous benefits when propagated as a desirable plant. They include providing a sustainable and highly nutritious source of livestock feed, reducing soil erosion, and increasing soil fertility.

Control 

  • Natural methods: Cutting and digging, mowing, burning
  • Chemical control: 2,2 DPA, and glyphosate + imazapyr

The best methods to prevent elephant grass growth are practicing crop rotation, maintaining healthy soil, and growing crops that can outcompete the grass.

For small infestations, cutting the plants and digging out the rhizomes will help eradicate the grass. 

Mowing the plants and treating the sprouted foliage with a chemical herbicide combination like glyphosate and imazapyr can provide effective control for larger infestations. 

When using any herbicide, it’s important to follow the manufacturer’s instructions and local regulations.