Hydriastele ramsayi

Hydriastele (high-dree-Ah-STEL-eh) ramsayi (ramz'-ee)
Northern Territory, Australia. Photo by Philippe Alvarez.
Scientific Classification
Genus: Hydriastele (high-dree-Ah-STEL-eh) Species: ramsayi (ramz'-ee)
Synonyms
Old name Gronophyllum ramsayi.
Native Continent
Oceania
Morphology
Habit: Solitary Leaf type: Pinnate
Culture
Survivability index
Common names
Northern Kentia Palm, gronnos

Habitat and Distribution

Northern Territory, Australia. Open eucalypt forest and rainforest edges.

Kakadu National Park, Northern Territory, Australia. Photo by Daryl O'Connor.

Distribution:—The central northern portion of Australia’s Northern Territory including the Cobourg Peninsula and Melville Island. Also reported from the north eastern portion of the territory (Dowe 2010).

Habitat:—Open eucalypt woodland dominated by seasonal drought and frequent wildfires, on sandstone slopes or flat ground on sandy soil, lowland. PETER PETOE, CHARLIE D. HEATUBUN & WILLIAM J. BAKER Phytotaxa 370 (1) © 2018 Magnolia Press.

Description

Solitary, robust palm to 30 m tall, bearing 9–17 leaves in crown. Stem 30–35 cm in diam., moderately ventricose. Leaf 1.5–3 m long including petiole; sheath about 100 cm long; petiole 30–80 cm long; rachis arcuate; leaflets 50–60 per side, arranged regularly, single-fold, ascending, linear acuminate to shallowly notched, ramenta lacking; middle leaflets about 80 × 2.5 cm. Inflorescence 50–60 cm long including 3.5–4.5 cm peduncle, branched to 2 orders, protandrous; prophyll often ± sigmoid, with pithy keels; rachillae ca. 31–32, not markedly sinuous; triads on average 5–6 mm apart, opposite and decussate. Staminate flower about 13 × 4 mm in bud (when dry), cream; stamens 5–6, exposed in bud. Pistillate flower about 5 × 4 mm in bud (when dry), green to cream, with free sepals and free petals with conspicuous, triangular and valvate tips. Fruit 12 × 6 mm (when dry), ellipsoid, red, with a distinct, dark, sclerotic zone encircling apical stigmatic remains (up to ca. 2 mm in diam.). Seed not seen; endosperm homogeneous. PETER PETOE, CHARLIE D. HEATUBUN & WILLIAM J. BAKER Phytotaxa 370 (1) © 2018 Magnolia Press.

Culture

Domesticating this species has proved slow, mainly due to the horrendous germination rate, 1% being usual, and this after waiting 12 months or more. Seed is planted in deep trays, as long brittle roots are formed. When finally the first strap leaf appears, extra care is needed moving them into pots, using one big enough to accommodate two years growth. Lightly fertilize and keep damp until 4 to 6 stiff bifid leaves are produced. Then they are planted out in dappled shade, as further growth seems unlikely, After gaining only 1 or 2 leaves in their first year they accelerate into more than normal growth rates, producing longer, pinnate, arching leaves. Plentiful water, good drainage and light fertilizing are necessary. (Palms & Cycads). Cold Hardiness Zone: 10b

Comments and Curiosities

"Firstly let me explain something. Hydriastele ramsayi grows in one of the most inhospitable hot climates on earth and trying to germinate seed has proven to be almost impossible out of it's own backyard. If you do have a plant, your chances of growing one succesfully would or should normally prove to be very difficult indeed, one would have to emulate the same type of environment, same soil, same heat, same humidity when needed. So what has our newest bestest honorary ratpack friend Craig from near Noosa done ? Well ladies and gees, he has done just that, he is growing one of these beauties so well, you'd think we were in Kakadu national park." (Walter John Donovan), see photos "Craig's palm" below.

"This is a majestic palm that grows in open woodland under extreme heat conditions. When we were there, we measured the temperature and humidity with a highly accurate electronic scientific thermometer. At the time it was 39°C (102°F) with 40% relative humidity ...stifling temperatures. Everything was hot to the touch, and the ground temperature was way in excess of 50°C (120°F). The wet season is still another month away, so the landscape is not as green as it can be, but some recent showers have taken away the scorched look. These palms were growing in almost pure sand, and could be found in all stages of development, from seedlings, through to young plants, juveniles and age-old monsters. Anyway, here are a few photos to give you a better idea of the growing conditions and the natural beauty of these palms." (Daryl O'Connor)