How to make Rhapis humilis flower?

[Pal Meir]

I still have two Rhapis humilis which germinated from seed in 2004. I hope that one might be a female tree and the other a male, because the growth behaviour of the two plants is different. As it is very hard to get seeds of R. humilis that are reliably from this species I intend producing some seeds, but my palms won’t bloom yet, although they are already 11 years old. Maybe it is because they were all the time inside a living room? Do you have any suggestions?

Here the two palms, planted together in a 28×28cm container (≈ 4gal):

[Phoenikakias]

In which respect do you think that those specimens have a different growth habit? I have a female Rhapis excelsa in pot that blooms every years and so did also a male excelsa in pot owned by a friend of mine. In both cases it is common that pot remain outdoors all year long.

[Pal Meir]

The (female?) one is more suckering, the other (male?) one is more growing in height. – Maibe you are right: I have to leave them more outdoors. Inside they can’t feel if it is the right season for flowering … But it is not possible here in Germany to leave the pot outside all the year long.

[Brucer]

Are you sure they are actually humilis?

I have rhapis humilis here in my garden and in pots in Sydney, and the new trunks of mine are much thicker, and the splits in the leaf when young are minimum of 9.

10-15 years ago, there were a lot of plants in Australia sold as humilis, but they were really subtilus.

My humilis in the ground are at least 5 metres tall.

[Geoff]

hmm… may be mistaken, but I was under the impression that 1) this plant only came in male, and 2) never seen/heard of 'seed' that could germinate producing a Rhapis humilis… perhaps you have some cross or something similar? Pretty sure these are only propagated by division.

[Brucer]

Yes, thats right Geoff, mine have never flowered, and only one sex is around, and they are only propagated by division.

[Pal Meir]

The natural habitat of Rhapis humilis was (re)discovered in the 1990s in the region of Guangxi (South China). The characteristics of R. humilis distinguishing it from R. excelsa or R. multifida are described by Hastings in Palms vol. 47 (2003):

http://www.palms.org/palmsjournal/2003/vol47n2p62-78.pdf

Especially the following features distinguish my two palms from R. excelsa:

“Rhapis humilis can be distinguished from R. excelsa by the leaf sheaths with intact ligule and neat fibers, closely sheathing the stem; blade semi-circular in outline, segments tapering at the apex with less regular secondary splitting, palman more

conspicuous; …” (Hastings 2003: 70-71)

Even the old ligules are still intact:

The blade is nearly circular, but quite different from R, multifida:

The stems of my palms ought to be thinner than the »usual« ones, because they are the first stems at all from the seedling and not the secundary stems resulting of suckering. Latters will be much thicker. Also that the juvenile leaves of the first suckers do not have so many leaflets as the leaves of later suckers is normal for suckering palms.

[LilikoiLee]

hmm… may be mistaken, but I was under the impression that 1) this plant only came in male, and 2) never seen/heard of 'seed' that could germinate producing a Rhapis humilis… perhaps you have some cross or something similar? Pretty sure these are only propagated by division.

Ah so, no wonder ours have never flowered!

[Phoenikakias]

hmm… may be mistaken, but I was under the impression that 1) this plant only came in male, and 2) never seen/heard of 'seed' that could germinate producing a Rhapis humilis… perhaps you have some cross or something similar? Pretty sure these are only propagated by division.

I have two clumping Rhapis plants growing next to each other, one bought as humilis and the other bought as subtilis. Both are male and I think the subtilis is rather a hybrid with maybe humilis in it though it grows taller and is less wind tolerant than the other humilis of mine. But the most conspicuous different between both plants appears during blooming season. The purported humilis blooms profusely, while the purported hybrid blooms considerably less. Maybe a poor blooming habit is an indication of hybridization! The following first two pictures show flower stalks of the purported humilis, while the last picture shows the inflorescence of the purported hybrid...

[Pal Meir]

My Rhapis subtilis, grown up from seed in 1981, looked a little bit different than yours; here the last photo taken in 2008, 27 years old (I gave it away to a zoologigal garden):

It bloomed relatively regularly because it was placed in a greenhouse, in contrast to my both R. humilis which were all the year inside an equally warm living room. Now I have placed those palms outdoors, hoping that they can feel the changing seasons and bloom sometime …

[Pal Meir]

One of my supposed Rhapis humilis (or robusta?) is starting flowering:

[Pal Meir]

Update 23 days later:

[Phoenikakias]

Until recently I was thinking that  I had specimens from Rhapis multifida of both genders, the one with the rich inflorescence with the smaller flowers being male and the other with the sparser inflorescence with the larger flowers being the female. And my impression was enhanced by the fact that the supposed male flowers never develop to fruits but the supposed female ones did so. But a friend of mine made me aware of the fact that male flowers on mulifida are not recorded and besides in the article of Principes I read that male flowers are larger on Rhapis genus. So now I am confused about its identity and about the gender of the large flowers, which most probably are hermaphrodite! Additionally it remains a mystery why the strictly female flowers have never set a single false fruit.

 

[Pal Meir]

… and here a side view (the taller tree won’t bloom yet):

[Pal Meir]

35 minutes ago, Phoenikakias said:

Until recently I was thinking that  I had specimens from Rhapis multifida of both genders, the one with the rich inflorescence with the smaller flowers being male and the other with the sparser inflorescence with the larger flowers being the female. And my impression was enhanced by the fact that the supposed male flowers never develop to fruits but the supposed female ones did so. But a friend of mine made me aware of the fact that male flowers on mulifida are not recorded and besides in the article of Principes I read that male flowers are larger on Rhapis genus. So now I am confused about its identity and about the gender of the large flowers, which most probably are hermaphrodite! Additionally it remains a mystery why the strictly female flowers have never set a single false fruit.

Male flowers are not recorded means only that they were unavailable to Hastings in 2003, but not that they were not available to others. And seeds were available also in the past, e.g. for myself in 2003 (pics below). And I suppose your guesses are correct, the full inflorescences are male, the sparse ones are female. (But I can’t decide on base of your photos if your Rhapis is R. multifida, but it looks so.)

[Pal Meir]

@Phoenikakias In all cases known to me male flowers of Rhapis spp. are much longer than female ones. The flowers of both of your Rhapis are very similar in shape to male flowers of R. excelsa.

[Howeadypsis]

Beautiful palms Pal!

[DoomsDave]

On 6/13/2015, 7:45:02, Phoenikakias said:

In which respect do you think that those specimens have a different growth habit? I have a female Rhapis excelsa in pot that blooms every years and so did also a male excelsa in pot owned by a friend of mine. In both cases it is common that pot remain outdoors all year long.

The outdoor part might be the key. Mutter Natur is better than any of us.

[Pal Meir]

20 minutes ago, DoomsDave said:

The outdoor part might be the key. Mutter Natur is better than any of us.

That’s the case: I could make at least one of the two palms bloom because I left them outdoors almost every day even during last winter.

[Pal Meir]

Will it be a girl? Will it be a boy? What will it be?  Which species … ???

[Pal Meir]

The coming inflorescence looks like R. cochinchinensis, but the description (Hastings 2003; Palmpedia) doesn’t fit. The leaves and the stem diameter are similar to R. siamensis, but the description (Henderson 2008, 2009) doesn’t fit … And so on, etc. etc. …

 

[Phoenikakias]

It's a boy! Or perhaps hermaphrodite?

 

 

 

 

 

 

 

 

 

 

i

[Pal Meir]

5 minutes ago, Phoenikakias said:

It's a boy! Or perhaps hermaphrodite?

Hmmmm …, we will see when the flowers open …  Here a contrasting drawing of Rhapis flowers (stolen from Genera Palmarum by ; that’s not me, I am ):

[Pal Meir]

And the taller one will bloom, too: It is showing the tip of the intrafoliar inflorescence prophyll.  I think it is later than the clustering other one because it was more exposed to the cold winds.

[Pal Meir]

Another pic with flash of the inflorescence of the suckering plant β (it is soooo dark today, you need even at daytime flashlight):

[Pal Meir]

Slowly unfolding, but still green: he, she, or it …?

[Pal Meir]

The inflorescence gets looking more and more like Rhapis cochinchinensis MART. 1838 ……

[Kai]

Amazing thread Pal, and great pictures! Could it be like some Chamaedorea that male plants flower a bit before the female plants do? In that case you might be expecting a female inflorescence and it would be wise to collect and store some pollen.

[Pal Meir]

… and two days later …:

[Pal Meir]

I always thought flowers were red and stalks green, but here it is upside-down ……

[Pal Meir]

We have quite chilly nights here (it’s summer solstice? ) so the development of the inflorescence is very slooooow …

[Phoenikakias]

Mein Freund Pal, it is obvious that up there in the gloomy north you don't see often blooming palms.  Many Rhapis spp (I don't have them all in my collection, so I can not   relate information to  the entire genus) have initially rachillae of pink color on the inflorescence, which subsequently as the flower buds grow to mature flowers turn green. This is the case with Rhapis humilis and excelsa.

[Pal Meir]

12 minutes ago, Phoenikakias said:

Mein Freund Pal, it is obvious that up there in the gloomy north you don't see often blooming palms.  Many Rhapis spp (I don't have them all in my collection, so I can not   relate information to  the entire genus) have initially rachillae of pink color on the inflorescence, which subsequently as the flower buds grow to mature flowers turn green. This is the case with Rhapis humilis and excelsa.

Thank you, dearest Phoenikakias, for your infos!  We don’t see not only often blooming palms here these days, but also a shining sun, so that I thought, here is everything upside-down, even the weather, which reminds me of winter solstice …

[Pal Meir]

Still waiting for summer and red flowers with green stalks …

In the meantime I have attached some explaning lables to the »interfoliar inflorescence«:

[Pal Meir]

The rachis bract is laterally splitting, so it seems to be Rhapis laosensis = R. cochinchinensis. (The persistent old leaf sheaths and ligules are still problematical: »Ocreas usually not persistent.«) And the flowers will turn to a yellowish colour and not become red …

[Pal Meir]

Here once more the characteristic laterally splitting of the rhachis bract:

[Pal Meir]

As the inflorescence of palm β seems to be pistillate (female) I hope the taller plant α will show staminate (male) flowers:

[Phoenikakias]

Here is the clump with two kinds of Rhapis, Both spp remain short (about 1.5 m) but this can be only a result of competition of many plant on a crowded spot. Any idea what kinds they may be? Depicted inflorescences belong to the broad leafed sp.

Edited July 1, 2016 by Phoenikakias

[Pal Meir]

@Phoenikakias The broad leaf Rhapis looks to me like R excelsa; the flowers seem to staminate (male).

Rhapis excelsa
(1) 2-15 leaflets
(2) blades not split to the base
(3) jagged apices of leaflets, straight sides
(4) petiole to 4 mm wide
(5) ligules not persistent
(6) stem with sheaths 1.5-2.1 cm diameter
(7) stem without sheaths 0.8-1.2 cm diameter
(8) stem to 3 m tall (Palmpedia: to 4 m)
(9) fruits yellow

The other palm with thin leaflets is hard to id; it looks a bit like R micrantha, but may be also an atypical R subtilis or so. I need better pics and the diameter of the stem. Here some infos to these two spp:

Rhapis micrantha
(1) 5-10 leaflets
(2) blades split to the base
(3) pointed apices of leaflets, curved sides
(4) petiole to 2.5 mm wide
(5) ligules not persistent
(6) stem with sheaths 1.7-1.8 cm diameter
(7) stem without sheaths 0.8-0.9 cm diameter
(8) stems 1-2 m tall
(9) fruits white

Rhapis subtilis
(1) 2-13 leaflets
(2) blades split to the base
(3) pointed apices of leaflets, curved sides
(4) petiole 0.9-3 mm wide
(5) ligules sometimes persistent
(6) stem with sheaths 0.6/8-2.0 (?) cm diameter
(7) stem without sheaths 0.3-2 cm diameter
(8) stem to 3 m tall
(9) fruits whitish, 0.5 cm

And a close-up of the inflorescence bracts would be very helpful for a more certain id.

 

[Pal Meir]

The flower stalks (rachillae) are getting paler and the rachis is already green, but the flowers won’t open yet; if the infos are correct the flowers should become yellowish and the bract curving down.